Give Scientific Reasons
 

1. Why does your voice sound different to you on a recording?

A- When you hear yourself speak regularly, the sound waves emanate through the tissue, bone, and other material, which changes its sound
B- When you hear yourself speak regularly, the sound waves bounce off who you are talking to, which changes its sound.
C- The speakers of the cassette recorder distort the sound of your recorded voice
D- I don't know


2. Do you move faster when swimming under the water or half-submerged?

A- You move faster under the water
B- You move faster when half submerged
C- I don't know

3. You are sitting in a baseball game in bleachers far from the field. You see the batter hit the ball and then you hear the crack of the bat. Why the delay?

A- The sound has to travel through a lot of material (all the people in the stadium) before it reaches your ear.
B- Light travels almost one million times faster than sound
C- Your brain anticipates what is going to happen visually, so you see the act a split second before it actually happens
D- You are too far away to hear the actual sound of the bat hitting the ball. What you hear is the echo of the actual sound.
E- I don't know

4. What are mirages?

A- Hallucinations of dehydrated wanderers
B- A mixture of gases that leak through fissures in the earth, mixing to create strange apparitions
C- Miniature whirlwinds blow sand in tight circles that seem to take shape from a distance
D- Optical phenomenon due to temperature differences of the surface and air directly above the surface
E- Low lying clouds
F- I don't know

5. Why does one sometimes have red-eyes in photographs?

A- The rays of the sun bounce off the lens of the camera, projecting a reddish glow into the eyes of those photographed
B- An ineffective flash doesn't allow enough light for the actual eye color to be recorded in the photo
C- A flash that is too glaring often makes people blink at the same time the shutter snaps. Therefore, the subjects eyes are merely blurred, though it appears red in the actual photo
D- The pupil doesn't have enough time to constrict and the picture records the reflection of the red retina in the back of the eye
E- I don't know

6. It is estimated that there are about 100 occurrences of lightning throughout the world each second. How many of these strike ground?

A- 75
B- 50
C- 25
D- 5
E- I don't know

7. Why is the moon small when it is high overhead in the sky, and large when it is near the horizon?


A- Near the horizon, the brain scales the size of the moon to trees and buildings
B- The moon is actually much closer when it is near the horizon, and thus appears larger.
C- The physical act of rolling the eyes upwards (towards the sky) encourages the brain to interpret objects to be smaller than they are.
D- When the moon is viewed near the horizon, one is actually viewing its reflection against the earth's ozone layer. This image is a shrunken version of the actual moon
E- I don't know

8. Which of the following has been known to curdle milk?

A- Sugar
B- Thunderstorms
C- Extremely loud music
D- Acidic soil
E- I don't know

9. Can pearls be found within mussels?

A- Yes
B- No
C- I don't know

10. What would happen if you soaked a raw egg in vinegar for 24 hours?

A- The yolk would turn green
B- It would disintegrate completely
C- The shell would turn rubbery
D- The shell would split perfectly in two
E- I don't know



Regards,
Sardarzada

1. [B]Question[/B]: Why does your voice sound different to you on a recording?
[B]Answer[/B]: When you hear yourself speak regularly, the sound waves emanate through the tissue, bone, and other material, which changes its sound.

2. [B]Question[/B]: Do you move faster when swimming under the water or half-submerged?
[B]Answer[/B]: You move faster under the water

3. [B]Question[/B]: You are sitting in a baseball game in bleachers far from the field. You see the batter hit the ball and then you hear the crack of the bat. Why the delay?
[B]Answer[/B]: Light travels almost one million times faster than sound.

4. [B]Question[/B]: What are mirages?
[B]Answer[/B]: Optical phenomenon due to temperature differences of the surface and air directly above the surface

5. [B]Question[/B]: Why does one sometimes have red-eyes in photographs?
[B]Answer[/B]: The pupil doesn't have enough time to constrict and the picture records the reflection of the red retina in the back of the eye.

6. [B]Question[/B]: It is estimated that there are about 100 occurrences of lightning throughout the world each second. How many of these strike ground?
[B]Answer[/B]: 25

7. [B]Question[/B]: Why is the moon small when it is high overhead in the sky, and large when it is near the horizon?
[B]Answer[/B]: Near the horizon, the brain scales the size of the moon to trees and buildings.

8. [B]Question[/B]: Which of the following has been known to curdle milk?
[B]Answer[/B]: Thunderstorms

9. [B]Question[/B]: Can pearls be found within mussels?
[B]Answer[/B]: Yes

10. [B]Question[/B]: What would happen if you soaked a raw egg in vinegar for 24 hours?
[B]Answer[/B]: The shell would turn rubbery

answer the question
 

kindly relpy this question as i found in previous everyday science papers

"Why man holes are round"

Pls reply and thanks...

Manholes need to be covered. Manholes, which interconnect underground sewerage pipes, and serve as a point of entry for cleaning the pipes, are located at every major sewer pipe junction, and are capped with round manhole covers. The reason for the circular construction of these covers is, quite simply, that covers of any other shape would fall through the manholes by virtue of their varying diameters. Circular manhole covers do not vary in width, or in diameter, as is the case with these other shapes, thus remaining in place despite the street traffic running roughshod over them.

Manufacturers craft the manhole covers together with the smaller sized lip, upon which they rest, at the same time to ensure a tightly sealed fit. Additionally, the manufacture of circular manhole covers is easier and more accurate than the manufacture of covers of any other shape. Lastly, round manhole covers, once removed, require less lifting and less manpower, as their shape allows them to be rolled.

Does the hump on camels hold water???
 

We heard since childhood that camels store water in their hump but its not very right.....Actually a camel's hump is a giant [B]mound of fat[/B]. In a healthy, well-fed camel, the hump can weigh as much as 80 pounds (35 kilograms)! Human beings and most animals store their fat mixed in with muscle tissue or in a layer right beneath the skin. Camels are the only animals with a hump.

The hump allows a camel to survive an extremely long time (up to two weeks) without food if need be. Because camels typically live in the desert, where food can be scarce for long stretches, this is important.

A camel uses about 5 gallons (20 liters) of water a day in the summer. However, a camel can lose up to 25 gallons (100 liters) of water from its body tissues without ill effects. [B]One thing that a camel can do to conserve water is to handle large body-temperature swings[/B]. A camel might start the day at 94 degrees F and allow its temperature to rise as high as 105 degrees F. Only at the upper end of this range does it need to sweat to prevent overheating. When you compare this temperature range to the range the human body can handle (where only a 2 degree rise indicates illness).Thts y people say camels the "Aircraft of Deserts".

why does the sky look blue?
 

Assalaam o alikum.
my name is ABDUL RAOUF BUTT. I am preparing for CSS.
i wana know why does the sky look blue?please help me because i did not found a comprehensive answer in any book.
thanks.

The sky looks blue because earth's atmosphere scatters sunlight. The sky is not actually blue, it only looks that way. It does not always look blue and even when it does it's not quite the same color or the same brightness everywhere. To scatter is to strew about aimlessly or to disperse. The atmosphere does that to light, but it scatters some colors better than others Sunlight is actually all the colors of the rainbow mixed together. The visible spectrum is the colors red, yellow, green, blue, indigo, and violet. Sunlight reaches us in the form of waves and each color consists of waves of a slightly different frequency. Of visible light, red has the lowest frequency and violet has the highest frequency. The frequencies of the other colors fall in between. At the end of the 19th century an English scientist, Lord Rayleigh, discovered that small particles do not scatter light in the same way as large particles. Air molecules are extremely small and scatter the high frequency violet and blue better than the low frequency red. Scattered sunlight contains more violet and blue than red but we see blue better than violet so the sky looks blue. At least it looks blue most of the time. At sunrise and sunset the sky is red, orange, or yellow. Rayleigh scattering is responsible, but the light passes through more air before it reaches our eyes. By the time the sunlight reaches us, scattering has removed the high frequencies to make blue skies for people on the part of earth where the sun is higher in the sky. Red light remains because it is scattered less. Big droplets of water which collect around bits of dust in the air to form a cloud or fog are too big for Rayleigh scattering. They scatter all colors equally so the clouds they form look white. Smaller water droplets which collect around dust or pollutants in the air form a yellowish haze.. Rayleigh scattering essentially absorbs the incoming light, then re-radiates it in all directions. We then see this scattered light coming to us from all directions. The scattered light is not only blue. It contains small amounts of the other colors as well, so the sky is not just blue. It is sky blue.

Reference:([url]http://home.honolulu.hawaii.edu/~rickb/SciColumns/BlueSky.08Apr95.html[/url])

Scientific Reasons
 

plz answer these questions


1# Why water boils quicker on mountains?
2# Why rainbow is produced in the sky after rainfall and sunlight?
3# Why water remains cool in Earthenware pitcher?
4# Why milk is considered as an ideal food?
5# Why meat takes longer to cook on the mountains?
6# Why ica and salt mixture is used as a freezing agent in manual ice-cream maker?
7# Why greenhouse operators paint their glass roof white in summer?

plz just go throughout the everyday science portion.....u will get the answers of most of ur questions...they r available

I have already gone through it and couldnt find what i m searching for . Plz help.

[B]The answer to ur q's are as follows:[/B]

1# Why water boils quicker on mountains?

[B]ANS:- This is becoz the atmospheric pressure on mountains is less and as a result the boiling temperature of water or temp. at wch water boils is reduced.....e.g. from 100 degrees centigrade to 97 or 98 degrees centigrade.
So it takes less time o reach this lower temp.[/B]

2# Why rainbow is produced in the sky after rainfall and sunlight?

[B]ANS: This is due to the splitting of sunlight into it's 7 basic colours: VIBGYOR.....after sunlight passes thru a raindrop and is a result of refraction.[/B]
3# Why water remains cool in Earthenware pitcher?

[B]ANS: This happens becoz when water evaporates from the surface of the pitcher a certain amount of energy or heat is required for evaporation or conversion of water droplets into water vapour so this heat is taken from the surface of the water in the pitcher and the water becomes cool.[/B]

4# Why milk is considered as an ideal food?

[B]ANS: Milk contains many of the nutrients and vitamins that are required for the body although the body can not survive on milke alone.[/B]

5# Why meat takes longer to cook on the mountains?

[B]ANS: As stated in answer to Q#1.....water boils at a lower temp. and a lower temp is reached by heating the cooking utensil so the meat only gets a lower temp. in wch it has to be cooked.....To solve this problem, the pressure cooker is used.....wch raises the tem of water above becoz of the increase in pressure on the water in the pressure cooker.[/B]

6# Why ice and salt mixture is used as a freezing agent in manual ice-cream maker?

[B]ANS: This is becoz salt reduces the temp. of the ice and stops the ice from melting and maintains the temp. and thus keeps the ice-cream cold.[/B]

7# Why greenhouse operators paint their glass roof white in summer?

[B]ANS: This is so that the white colour will reflect all the sunlight back and thus prevents the greenhouse from over-heating as white colour has the property of reflecting light and heat.[/B]

[B]If u have any more q's just ask me....or ask me @ Questions!!! or at this link: [url]http://www.cssforum.com.pk/central-superior-services-examination/beginners-guide/8327-questions.html[/url][/B]

Let's Discuss Scientific Reasons
 

[B]Q. Color Blindness and Haemophilia are more common in men than in women..[/B]

ANS: Color blindness and Haemophilia are genetic diseases related to "Sex Chromosomes". For understanding the cause, first one must know the Basic of genetics. The following discussion will also contain some notes regarding basic information and finally the answer for the scientific reasons.


[B]CHROMOSOMES[/B]:

In humans there are 46 chromosomes in the nucleas of the Cell. Each chromosomes out of 46 has a pair; therefore, there are 23 pair of chromosomes.

[B]SEX CHROMOSOMES:[/B]

Out of 23 pair there is one pair of chromosome that is called "Sex Chromosome" pair. Male have "XY" chromosomes as a pair and females have "XX" chromosomes in a pair. The "Y" chromsome in "XY" Chromosome pair in male dummy and only "X" chromosome is functional in the "XY" pair. While in females, one of the "X" is fully functional just like in male, but the other "X" is partially functional.

[B]AUTOSOMES[/B]:

Chromosomes other than sex chromosomes are called "AUTOSOMES". Therefore, there are 22 pair of "AUTOSOMES" and 1 pair of "SEX CHROMOSOMES": 22 Autusomes pair + 1 pair of sex chromosomes = total 23 pair of chromosomes

[B]TRAIT: [/B]

Any characteristic in human body that is expressed by a single or a group of genes is called trait; for example, eye color, skin color, hair color, etc

[B]GENES:[/B]

Each chromosome has several genes located on it. A single Gene is the unit of trait that our body have, for example, the eye color, blood group, etc. It is not necessary that one gene control a single "trait"; for example, there are different genes that control a single trait as Height, Skin color, etc.

Just as a chromosome has a pair, in the say way, every gene has a pair in the other pairing chromosome.


[B]Recessive trait and Dominant Trait[/B]

Take an example of eye color; there are various colors of eyes in human, some have black, some have blue, some have hazel, etc. The most common is black. Now consider the situation on genetic level; if in a pair of chromosome, one chromosome has a black eye color gene and the other has blue; then black will be prevalent and expressed in a human body. Therefore, the blue color is recessive and the black is dominant. Blue color of eyes will express itself when there will be both "blue" trait gene in both of pair of chromosomes.


[B]Now, come to the point of HAEMOPHILIA AND COLOR BLINDNESS:[/B]

If there happens to be a gene for "Color blindness" (that is "Recessive" in its nature like my above example for blue eyes color) in X choromosome in male as well as in female. Due to lack of one "X" chromosome in male "XY" sex chromosome, the recessive trait of "Color blindness" will express itself. However, in case of females, there are two "XX" chromsomes and one is partially functional, therefore, if a female have a "Color Blindness" trait on one "X" and absent in the other "X", then the female will not suffer from "Colorblindness "; to be "color-blind" the female needed to have "color-blind" gene on both of the pair of sex chromosomes.

Therefore, due to lack of one "X" chromosome in male it is more prevalent or common in male, while in female both "XX" chromosomes decrease the prevalance of the "Color blindness".


[B]What is a color blind carrier?[/B]

ANS: When a female has has one colorblind gene in one chromosomes in a pair of gene while the other chromosome is normal; then the female is said to be "Carrier" however, she is not diseased with "Colorblindness".



[B]Diagramatic Expression:
======================[/B]

C = chromosome containing color blind Gene
X = Normal Chromosome

[B](A) WHEN A COLOR BLIND FEMALE MARRIES WITH A COLOR BLIND MALE
--------------------------------------------------------------
[/B]


Color Blind Male (CY) Color Blind Female (CX)



. .
. .
. .
. .
. .

CC , CX , CY , XY


CC = Color blind Female

CX = Carrier Female

YC = Color Blind Male

XY = Normal Male


[B](B) WHEN A COLOR BLIND MAN MARRIES WITH A NORMAL FEMALE
----------------------------------------------------------[/B]


Color Blind Male (CY) Normal Female (XX)

. .

. .

. .

. .

CX, CX, XY, XY

CX = Color blind female

CX = Color Blind female

XY= Normal male

XY = Normal male

Give Scientific Reasons
 

[B]All the respected senior members are requested to post the scientific reasons for the questions given below . Especially the moderators are requested to do the needful ! I could not found them in my book .[/B]

Q.1) Why the front wheels of vehicle lean outwards slightly ?
Q.2) Why do peoples voices sound differently ?
Q.3) why is it easier to push a heavy grass mover than to lift it ?
Q.4) Why is an electric bulb less efficient than a fluorescent tube ?
Q.5)How does the pouring of kerosene oil on stagnant on stagnant water contribute to the eradication of malaria ?
Q.6)Why is it dangerous to have charcoal fire burning in a badly ventilated room ?
Q.7)The works output of a machine is always equal to the work input ?
Q.8)All motions are relative to one another ?
Q.9)Gravity of all the objects is same, regardless of their mass of at a give point on the earth's surface.?
Q.10)Why do you hear thunder after and see flash of light first ?
Q.11)why a bomber does not drop bomb when it is vertically above the target ?
Q.12)Transmission lines carry very high voltages ?
Q.13)A ball dropped vertically on the ground does not rise to its original height ?
Q.14)More stirring is needed when sugar is dissolved in cold cofee than in hot coffee ?
Q.15)Lunar eclipse lasts much longer than solar eclipse ?
Q.16)Goiter is common among people living in hilly areas ?
Q.17)Detergents are better cleaning agent as compared to soaps ?
Q.18) decomposers are imp for life and land and water ?
Q.19)Places near the sea are cooler in summer and warmer in winter than places farther in-land ?
Q.20)A 25 watts incandescent bulb provides much less light than a 25 watts fluorescent tube light ?

These questions aforementioned are from past papers , Every one is requested to please spare some time to figure them out !
take care

[quote]Why do you hear thunder after and see flash of light first ?[/quote]

I think, light and sound are produced at the same time, but we see the flash first and light later because of light's speed, i.e. faster than the speed of sound



Please rectify me if m' wrong.

[QUOTE]Lunar eclipse lasts much longer than solar eclipse ?[/QUOTE]
Lunar eclipse last longer than the solar eclipse because the length of the earth’s umbral shadow cone is more than three times the average distance between the moon and the earth, so the shadow is relatively wide at the point where the moon crosses it.
[QUOTE]
Goiter is common among people living in hilly areas ?[/QUOTE]
Goiter is common in hilly areas because there is deficiency of Iodine in the water.
[QUOTE]
Detergents are better cleaning agent as compared to soaps ?[/QUOTE]
A detergent consists of hydrophilic and hydrophobic ends. In case of dirt the detergent pushes the dirt off the surface of the wet surface of the fabric. The washing machine provides the agitation.

[QUOTE] Decomposers are imp for life and land and water ?[/QUOTE]
An Ecosystem comprises of produces consumers and decomposers. The decomposers are bacteria and Fungi which degrade organic matter.
[QUOTE]
Places near the sea are cooler in summer and warmer in winter than places farther in-land ?[/QUOTE]
Sea water keeps the temperature moderate. Because of high specific heat it takes longer for water to get heated up or to get cooled. During summer days the land near the sea gets heated up quickly but the sea water remains cool and thus cool breeze blowing from the sea reduces the heat in the adjoining land area. the land gets cooled quicker but the sea water remains warm and thus the land gets warm breeze from the sea. But the land farther inside does not have this advantage. This accounts for the difference in the climatic conditions.

[QUOTE]A 25 watts incandescent bulb provides much less light than a 25 watts fluorescent tube light ?[/QUOTE]
When electric current passes through the fluorescent lamp, the mercury gets very hot and changes to a gas. A short of rays is given off by the gas. The rays when strike against a coating of special material inside the glass tube, it makes the special material glow.

[QUOTE]More stirring is needed when sugar is dissolved in cold coffee than in hot coffee ?[/QUOTE]
In hot coffee, the kinetic energy of the molecules is greater because of the high temperature range in it. According to kinetic molecular theory this is not possible in cold coffee. So it is difficult to dissolve sugar in it.
[QUOTE]
A ball dropped vertically on the ground does not rise to its original height ?[/QUOTE]
All the energy is converted from potential energy to kinetic energy.

[quote] why is it easier to push a heavy grass mover than to lift it ?[/quote] The principle of lever works in pushing a heavy grass mover. With the help of lever we can push the heavy things and even lift them. Moreover the gravity of the earth is 9.8 that attract each object. With this force while lifting the grass mover more force is required then pushing it.

[quote]why a bomber does not drop bomb when it is vertically above the target ?[/quote] Any particle or body which has horizontal motion and at the same time acts like a falling body can be classified as a projectile. It may seem a bit odd that the horizontal motion has no effect on the vertical motion or vice versa, but nevertheless this is true if air resistance is neglected. If a projectile is fired horizontally, it will have a velocity in that direction equal to that given it initially. At the same time it is travelling horizontally, it will fall toward earth, due to gravitational forces exerted on it. While the horizontal motion is at constant velocity the vertical motion is accelerated. This is the reason that a bomber does not drop a bomb when it is vertically above the target.
[quote]
The works output of a machine is always equal to the work input ?[/quote] The work done on a machine or the energy provided to the machine is called input. Let effort P acts through a distance d then work done on machine is Pd.

[CENTER][LEFT] Input = Effort x Distance through which the efforts acts

i.e. Input = P x d
[/LEFT]

[/CENTER]
The work done by the machine is called output. If a machine overcomes a force W through distance D, then the useful work done by the machine is W x D. Thus:

Output = Weight x Distance through which the weight acts
i.e. Output = W x D

If we think of an ideal machine which has output equal to the input, the efficiency of an ideal machine is thus one or 100. Thus for an ideal machine:

[CENTER] Output = Input
P x d = W x d
[/CENTER]
[quote]
Gravity of all the objects is same, regardless of their mass of at a give point on the earth's surface?[/quote] If we drop a body from a certain height, it falls to the ground and its velocity continues to increase till it strikes the ground. The body, therefore, gets accelerated as it falls freely, whether light or heavy objects are dropped, they will reach the ground at the same time and the acceleration will reach the ground at the same time and the acceleration will be the same.

@last island

can u please illuminate this a bit more

"All the energy is converted from potential energy to kinetic energy"..
thanks

[QUOTE]can u please illuminate this a bit more
"All the energy is converted from potential energy to kinetic energy"..[/QUOTE]
[QUOTE]A ball dropped vertically on the ground does not rise to its original height ?
[/QUOTE]
When the ball is hit on the ground, this work (called potential energy) goes to accelerate the ball (and now is called kinetic energy). When the ball hits the floor this kinetic energy is converted into heat and sound by the impact.
During the bounce, it squashes and comes to a complete stop. As it springs back to its original shape it pushes itself back up off the surface and jumps off the surface like a person doing a standing jump. It can’t bounce back to its original drop height since energy is lost in the ball when it squashes. Most of the energy loss is due to friction inside the ball and it goes into heating the ball. The ball temperature increases slightly every bounce.

[QUOTE]Why do you hear thunder after and see flash of light first ?[/QUOTE]
A flash of lightning heats the air around it. Then the air moves outward quickly, making the sound of thunder. We see lightning the instant it lights up the sky. But the sound of thunder moves more slowly through the air. So it always comes after we see the lightning. Sometimes, especially at night, we may see lightning, but not hear the thunder because it is too far away

[B]1. Why the front wheels of vehicle lean outwards slightly ?
2. Why do peoples voices sound differently ?
4. Why is an electric bulb less efficient than a fluorescent tube ?
5. How does the pouring of kerosene oil on stagnant on stagnant water contribute to the eradication of malaria ?
6. Why is it dangerous to have charcoal fire burning in a badly ventilated room ?
8. All motions are relative to one another ?
12. Transmission lines carry very high voltages ?[/B]

7 questions are left to be answered. Can anybody answer them?

To further elaborate:

Quote:
[B]More stirring is needed when sugar is dissolved in cold coffee than in hot coffee ? [/B]

In hot coffee, the kinetic energy of the molecules is greater because of the high temperature range in it. According to kinetic molecular theory this is not possible in cold coffee. So it is difficult to dissolve sugar in it.

The saturation capacity of any liquid is low during low level of kinetic energy of its molecules. When we increase the kinetic energy by heating or stirring the solute content holding capacity of liquid molecules is increased likewise its saturation level also increased and it can hold more sugar contents.

Quote:
[B]A ball dropped vertically on the ground does not rise to its original height ? [/B]

The ball pushes itself back as per Newton's third law of motion every action has reaction in same amount but in opposite direction. When ball hit on the ground, its kinetic energy is converted into heat and sound. During bounce, it has to pass through the surrounding air and move with the force of gravity. During its way to ground gravitation force help it while during its way back gravitation force hinder its movement. the friction from surrounding air and also consumes its kinetic energy so with the efforts of heat, sound, gravitational force and friction of surrounding air the ball cannot reach upto the level of its drop.

[B]5. How does the pouring of kerosene oil on stagnant on stagnant water contribute to the eradication of malaria ?[/B]

malaria is caused by a micro organism 'plasmodium' which lives in Anophelas mosquitoes (perhaps there are two main types of mosquitos perhaps first is cules and anophelas- culex infect birds while anophelas to animals).

mosquito goes through different stages during its development/growth i.e. egg, larvae, pupae and flying mosquito. first three stages are completed in water.

mosquito lay eggs on stagnant water. when keronsene oil is poured in small ponds of stagnant water it covers its upper layer and do not allow air to move inside layers of the water pond. the larvae of mosquito needs air/oxygen to breath, and it come from time to time on water layer to breath, in absence of oxygen mosquito larvae die out. the same process is related with other water animals like fish, if oil is poured into water then animal life inside that water is disturbed badly. other forms of oil can also be utilized but kerosene oil is a bit cheap thats why it is favoured.

i rememberd four five years back that in front plot of my home there was stangnant water, we got petrol from the vehicle and poured on the water and after some time we lit it and with a flash of fire all petrol burnt down and many mosquito larvae-which came near layer of water died out and we witnessed their dead bodies flowing in water...

[B]6. Why is it dangerous to have charcoal fire burning in a badly ventilated room ?[/B]

charcoal require oxygen to burn and to produce carbon dioxide, if it is burnt in badly vetilated room tu it can utilize al of its oxygen and producing much carbon dioxide and life can be fatal in such room. further the fume badly detriot the lungs and respiratory passage....

@Tabassum shabbir

Thank you very much for further elucidation . And still 5 questions are left .
Is there any one who can give scientific reasons for the questions left, sir suresh is requested to do the needful soon he interacts with the post .


[B]
1. Why the front wheels of vehicle lean outwards slightly ?
2. Why do peoples voices sound differently ?
4. Why is an electric bulb less efficient than a fluorescent tube ?
5. All motions are relative to one another ?
6. Transmission lines carry very high voltages ?[/B]

1. Why the front wheels of vehicle lean outwards slightly ?

Answer: As viewed from the front or rear of the vehicle, camber refers to the "lean" of the wheel from top to bottom. A wheel that leans outward at the top (compared to true vertical) has positive camber. One that leans inward at the top has negative camber. If the wheel is oriented in a true vertical, it's called zero camber.
Camber must always be adjusted to maximize the tread contact patch based on the driving requirements. In most cases, OE specifications will recommend a slightly positive or zero camber to maximize tire wear and traction, and to provide easier steering and greater resistance to directional darting in a straight line.
If the wheel features a static negative camber angle (vehicle sitting idle), this places more tread load at the road surface on the inner shoulder and tread area. Negative camber is regularly employed on performance vehicles (especially race cars on road courses) in order to increase the tire contact patch during hard turns. Since lateral loading (when a car goes into a hard turn) will try to push the top of the inside tire outward, an adequate negative camber angle may compensate for this. So, while the front wheels may display negative camber as the vehicle rolls light, when it goes into a hard turn, ie wheel facing the direction of the turn will try to "straighten up," achieving maximum tread contact with the road. If camber isn't sufficiently negative, this tire would lean too far, causing the inside of the tread to lift and placing excess stress and load only on the outside of the tread and outer shoulder.

Sound is generated in the larynx, and that is where pitch and volume are manipulated. The strength of expiration from the lungs also contributes to loudness, and is necessary for the vocal folds to produce speech.
Fine manipulation of the larynx is used in a great way to generate a source sound with a particular fundamental frequency, or pitch. This source sound is altered as it travels through the vocal tract, configured differently based on the position of the tongue, lips, mouth, and pharynx. The process of altering a source sound as it passes through the filter of the vocal tract creates the many different sounds.
The vocal folds can be held close together (by adducting the arytenoid cartilages), so that they vibrate (see phonation). The muscles attached to the arytenoid cartilages control the degree of opening. Vocal fold length and tension can be controlled by rocking the thyroid cartilage forward and backward on the cricoid cartilage, and by manipulating the tension of the muscles within the vocal folds. This causes the pitch produced during phonation to rise or fall.

It is highly unlikey to find all these voluntary and involuntry movements taking place to produce sound similar in all individuals. That is why, people voices sound differently.

4. Why is an electric bulb less efficient than a fluorescent tube ?

Answer: My dear, in ordinary electric bulb, electic energy is being converted into light energy and heat energy as the tungston filament resists to the flow of electricity and gets hoter and glows.
A fluorescent lamp is a gas-discharge lamp that uses electricity to excite mercury vapor in argon or neon gas, resulting in a plasma that produces short-wave ultraviolet light. This light then causes a phosphor to fluoresce, producing visible light.
The main principle of fluorescent tube operation is based around inelastic scattering of electrons. An incident electron (emitted from the coils of wire forming the cathode electrode) collides with an atom in the gas (such as mercury, argon or krypton) used as the ultraviolet emitter. This causes an electron in the atom to temporarily jump up to a higher energy level to absorb some, or all, of the kinetic energy delivered by the colliding electron. This is why the collision is called 'inelastic' as some of the energy is absorbed. This higher energy state is unstable, and the atom will emit an ultraviolet photon as the atom's electron reverts to a lower, more stable, energy level. The photons that are released from the chosen gas mixtures tend to have a wavelength in the ultraviolet part of the spectrum. This is not visible to the human eye, so must be converted into visible light. This is done by making use of fluorescence. This fluorescent conversion occurs in the phosphor coating on the inner surface of the fluorescent tube, where the ultraviolet photons are absorbed by electrons in the phosphor's atoms, causing a similar energy jump, then drop, with emission of a further photon. The photon that is emitted from this second interaction has a lower energy than the one that caused it. The chemicals that make up the phosphor are specially chosen so that these emitted photons are at wavelengths visible to the human eye. The difference in energy between the absorbed ultra-violet photon and the emitted visible light photon goes to heat up the phosphor coating.
The principle working in fluroescent tube is more efficient and this is the answer to your question.

Question 5. All motions are relative to one another ?

Answer: This belongs to the theory of relativity. Whenever you observe the motion of an object, your observations are relative to your own frame of reference. Let me give you an example. You are traveling in your car and your mobile phone is lying on the dash board. Movement is defined by the change in displacement. The distance between you and your mobile phone is not changing and hence you will observe that the mobile is not moving. Now you pass by a pedestrian walking on the footpath. The distance between him and your mobile phone is changing. So according to him, your mobile phone is moving. So the movement is always relative to the frame of reference. Since your frame of reference and that of the pedestrian were different, so the observations were different.

6. Transmission lines carry very high voltages ?

Voltage is simply the potential difference. At higher potential difference, electricity can be transferred more efficiently. That is why, the potential difference is kept higher when electricity is to be transferred to remote areas.

[QUOTE]Q.2)' Why do peoples voices sound differently ?[/QUOTE]that is mainly because the "quality" of the sound. you might have the same pitchand amplitude but the quality of teh sound differentiates the two sounds.[QUOTE]Q.6)Why is it dangerous to have charcoal fire burning in a badly ventilated room ?[/QUOTE]the burning of charcoal produces carbon monoxide and carbon dioxide. both of them are toxic. in a closed room they take the place of oxygen which is necesssary for breathing.[QUOTE]Q.11)why a bomber does not drop bomb when it is vertically above the target ?[/QUOTE]because of inertia. the bomb is travelling with the plane when it is dropped it is still in motion. so it keeps moving. the gavity acts on it and it makes a projectile due to that.

[B][U][CENTER][SIZE="6"][COLOR="DarkRed"]
Scientific reasons[/COLOR][/SIZE][/CENTER][/U][/B]


1. [B]If blood is red, why are veins blue?[/B]

Blood is bright red in its oxygenated form and a dark red in deoxygenated form. In simpler terms, it is bright red when it leaves the lungs full of oxygen and dark red when it returns to the lungs for a refill. Veins appear blue because light penetrating the skin is absorbed and reflected in high energy wavelengths back to the eye. Higher energy wavelengths are blue.


2. [B]Why is the sky blue ?[/B]

When sunlight travels through the atmosphere, it collides with gas molecules. These molecules scatter the light. The shorter the wavelength of light, the more it is scattered by the atmosphere. Because it has a shorter wavelength than the other colours, blue light is scattered more, ten times more than red light, for instance. That is why the sky is blue.

Why does the setting sun look reddish orange? When the sun is on the horizon, its light takes a longer path through the atmosphere to reach your eyes than when the sun is directly overhead. By the time the light of the setting sun reaches your eyes, most of the blue light has been scattered out. The light you finally see is reddish orange, the colour of white light minus blue.




3. [B]Why do onions make you cry?[/B]

Onions, like other plants, are made of cells. The cells are divided into two sections separated by a membrane. One side of the membrane contains an enzyme which helps chemical processes occur in your body. The other side of the membrane contains molecules that contain sulfur. When you cut an onion, the contents on each side of the membrane mix and cause a chemical reaction. This reaction produces molecules such as ethylsufine which make your eyes water.

To prevent crying when you cut an onion, cut it under a running tap of cold water. The sulfur compounds dissolve in water and are rinsed down the sink before they reach your eyes. You can also put the onion in the freezer for ten minutes before you cut it. Cold temperatures slow down the reaction between the enzyme and the sulfur compounds so fewer of the burning molecules will reach your eyes.




4. [B]Why does wet fabric appear darker?[/B]

When fabric gets wet, light coming towards it refracts within the water, dispersing the light. In addition, the surface of the water causes incoherent light scattering. The combination of these two effects causes less light to reflect to your eyes and makes the wet fabric appear darker.

[B]1. [/B][B]Question:[/B] A man with a load jumps from a high building. What will be the load experienced by him?
[B]Answer:[/B] Zero, because while falling, both the man and the load are falling at the same acceleration i.e. acceleration due to gravity.

[B]2.[/B] [B]Question:[/B] A piece of chalk when immersed in water emits bubbles. Why?
[B]Answer:[/B] Chalk consists of pores forming capillaries. When it is immersed in water, the water begins to rise in the capillaries and air present there is expelled in the form of bubbles.

[B]3.[/B] [B]Question:[/B] Why does a liquid remain hot or cold for a long time inside a thermos flask?
[B]Answer:[/B] The presence of air, a poor conductor of heat, between the double glass wall of a thermos flask, keeps the liquid hot or cold inside a flask for a long time.

[B]4.[/B] [B]Question:[/B] Why does a ball bounce upon falling?
[B]Answer:[/B] When a ball falls, it is temporarily deformed. Because of elasticity, the ball tends to regain its original shape for which it presses the ground and bounces up (Newton's Third Law of Motion).

[B]5[/B] [B]Question:[/B] Why is standing in boats or double decker buses not allowed, particularly in the upper deck of buses?
[B]Answer:[/B] On tilting the centre of gravity of the boat or bus is lowered and it is likely to overturn.

[B]6.[/B] [B]Question:[/B] Why is it recommended to add salt to water while boiling dal?
[B]Answer:[/B] By addition of salt, the boiled point of water gets raised which helps in cooking the dal sooner.

[B]7. [/B][B]Question:[/B] Why is it the boiling point of sea water more than that of pure water?
[B]Answer:[/B] Sea water contains salt, and other impurities which cause an elevation in its boiling point.

[B]8.[/B] [B]Question:[/B] Why is it easier to spray water to which soap is added?
[B]Answer:[/B] Addition of soap decreases the surface tension of water. The energy for spraying is directly proportional to surface tension.

[B]9. [/B][B]Question:[/B] Which is more elastic, rubber or steel?
[B]Answer:[/B] Steel is more elastic for the same stress produced compared with rubber.

[B]10[/B]. [B]Question:[/B] Why is the sky blue?
[B]Answer:[/B] Violet and blue light have short waves which are scattered more than red light waves. While red light goes almost straight through the atmosphere, blue and violet light are scattered by particles in the atmosphere. Thus, we see a blue sky.

[B]11. [/B][B]Question:[/B] Why Does ink leak out of partially filled pen when taken to a higher altitude?
[B]Answer:[/B] As we go up, the pressure and density of air goes on decreasing. A Partially filled pen leaks when taken to a higher altitude because the pressure of air acting on the ink inside the tube of the pen is greater than the pressure of the air outside.

[B]12.[/B] [B]Question:[/B] On the moon, will the weight of a man be less or more than his weight on the earth?
[B]Answer:[/B] The gravity of the moon is one-sixth that of the earth; hence the weight of a person on the surface of the moon will be one-sixth of his actual weight on earth.

[B]13. [/B][B]Question:[/B] Why do some liquid burn while others do not?
[B]Answer:[/B] A liquid burns if its molecules can combine with oxygen in the air with the production of heat. Hence, oil burns but water does not.

[B]14.[/B] [B]Question:[/B] Why can we see ourselves in a mirror?
[B]Answer:[/B] We see objects when light rays from them reach our eyes. As mirrors have a shiny surface, the light rays are reflected back to us and enter our eyes.

[B]15. [/B][B]Question:[/B] Why does a solid chunk of iron sink in water but float in mercury?
[B]Answer:[/B] Because the density of iron is more than that of water bus less than that of mercury.

[B]16. Question:[/B] Why is cooking quicker in a pressure cooker?
[B]Answer[/B]: As the pressure inside the cooker increases, the boiling point of water is raised, hence, the cooking process is quicker.

[B]17. Question:[/B] When wood burns it crackles. Explain?
[B]Answer:[/B] Wood contains a complex mixture of gases and tar forming vapors trapped under its surface. These gases and tar vapors escape, making a cracking sound.

[B]18. Question:[/B] Why do stars twinkle?
[B]Answer:[/B] The light from a star reaches us after refraction as it passes through various layers of air. When the light passes through the earth?s atmosphere, it is made to flicker by the hot and cold ripples of air and it appears as if the stars are twinkling.

[B]19. Question:[/B] Why is it easier to roll a barrel than to pull it?
[B]Answer:[/B] Because the rolling force of friction is less than the dynamic force of sliding friction.

[B]20. Question:[/B] If a feather, a wooden ball and a steel ball fall simultaneously in a vacuum, which one of these would fall faster?
[B]Answer:[/B] All will fall at the same speed in vacuum because there will be no air resistance and the earth?s gravity will exert a similar gravitational pull on all.

[B]21. Question:[/B] When a man fires a gun, he is pushed back slightly. Why?
[B]Answer:[/B] As the bullet leaves the nozzle of the gun?s barrel with momentum in a forward direction, as per Newton's Third Law of Motion, the ejection imparts to the gun as equal momentum in a backward direction.

[B]22. Question:[/B] Ice wrapped in a blanket or saw dust does not melt quickly. Why?
[B]Answer[/B]: Both wood and wool are bad conductors of heat. They do not permit heat rays to reach the ice easily.

[B]23. Question:[/B] Why do we perspire on a hot day?
[B]Answer:[/B] When the body temperature rises, the sweat glands are stimulated to secrete perspiration. It is nature's way to keep the body cool. During the process of evaporation of sweat, body heat is taken away, thus giving a sense of coolness.

[B]24. Question:[/B] Why does ice float on water but sink in alcohol?
[B]Answer[/B]: Because ice is lighter than water it floats on it. However, ice is heavier than alcohol and therefore it sinks in alcohol.

[B]25. Question:[/B] Why do we perspire before rains?
[B]Answer:[/B] Before the rain falls, the atmosphere gets saturated with water vapors; as a result, the process of evaporation of sweat is delayed.

26. [B]Question:[/B] Why does a thermometer kept in boiling water show no change in reading after 1000C?
[B]Answer:[/B] The boiling point of water is 1000C. Once water starts boiling at this temperature, thermometer records no change in temperature. The quantity of heat supplied is being utilized as latent heat of evaporation to convert the water at boiling point into vapour.

27. [B]Question:[/B] Why do we bring our hands close to the mouth while shouting across to someone far away?
[B]Answer:[/B] By keeping hands close to mouth the sound is not allowed to spread (Phenomenon of diffraction of sound) in all direction, but is directed to a particular direction and becomes louder.

28. [B]Question:[/B] Why does a corked bottle filled with water burst if left out on a frosty night?
[B]Answer:[/B] Because of low temperature the water inside the bottle freezes. On freezing it expands, thereby its volume increases and pressure is exerted on the walls.

29. [B]Question:[/B] Why is a small gap left at the joint between two rails?
[B]Answer:[/B] To permit expansion of rails due to heat generated by friction of a moving train.

30. [B]Question:[/B] Why cannot a copper wire be used to make elements in electric heater?
[B]Answer:[/B] Copper melts at 108.30C and forms a black powder on reacting with atmospheric oxygen. For heater elements a metal should have more resistance to produce heat.

31. [B]Question:[/B] Why are water or mercury droplets always round when dropped on a clean glass?
[B]Answer:[/B] The surface of a liquid is the seat of a special force as a result of which molecules on the surface are bound together to form something like a stretched membrane. They tend to compress the molecules below to the smallest possible volume, which causes the drop to take a round shape as for a given mass he sphere has minimum volume.

32. [B]Question:[/B] Why does a balloon filled with hydrogen rise in the air?
[B]Answer:[/B] Weight of hydrogen is less than the weight of air displaced by it. In balloons hydrogen is normally filled because it is lighter than air.

33. [B]Question:[/B] Why do we lean forward while climbing a hill?
[B]Answer:[/B] In order to keeps the vertical line passing through our centre of gravity always between our feet, which is essential to attain equilibrium or stability.

34. [B]Question:[/B] Why does smoke curl up in the air?
[B]Answer:[/B] Smoke contains hot gases which being lighter in weight, follows a curved path because of the eddy currents that are set up in the air.

35. [B]Question:[/B] Why does an electric bulb explode when it is broken?
[B]Answer:[/B] The bulb encompasses partial vacuum and as it breaks, air rushes in causing a small explosion.

36. [B]Question:[/B] Why does a man fall forward when he jumps out of a running train or bus?
[B]Answer:[/B] He is in motion while in the train or bus. When he jumps out, his feet comes to rest while touching the ground but his upper portion which is still in motion propels him forward.

37. [B]Question:[/B] Why does an ordinary glass tumbler crack when very hot tea or milk is poured in it?
[B]Answer:[/B] When a hot liquid is poured into a tumbler, the inner layer of the tumbler gets heated, it expands before the outer layer and an unequal expansion of both layers causes the tumbler to crack.

38. [B]Question:[/B] Why is a compass used as an indicator of direction?
[B]Answer:[/B] The magnetic needles of a compass under the influence f the earth?s magnetic field lie in a north-south direction. Hence, we can identify direction.
39. [B]Question:[/B] Why is water from a hand pump warm in winter and cold in summer?
[B]Answer:[/B] In winter, the outside temperature is lower than that of water flowing out of the pump, and therefore, the water is warm. Whereas in summer, the outside temperature is higher than the water of the pump, and therefore, it feels cold.

41. [B]Question:[/B] Why is a rainbow seen after a shower?
[B]Answer:[/B] After a shower, the clouds containing water droplets act like a prism through which the white light is dispersed producing a spectrum.

42. [B]Question:[/B] Why does a swimming pool appear less deep than is actually is?
[B]Answer:[/B] The rays of light coming from the bottom of the pool pass from a denser medium (water) to a rarer medium (air) and are refracted (bend away from the normal). When the rays return to the surface, they form an image of the bottom of the pool at a point, which is little above the real position.

43. [B]Question:[/B] Why is one?s breath visible in winter but not in summer?
[B]Answer:[/B] In winter, water vapor contained in the breath condenses into small droplets, which become visible but in summer they are quickly evaporated and not seen.

44. [B]Question:[/B] Why doesn?t the electric filament in an electric bulb burn up?
[B]Answer:[/B] Firstly, because is made of tungsten which has a very high melting point (34100C) whereas the temperature of the filament required to glow is only 2700oC. Secondly, oxygen is absent since the bulb is filled with an inert gas which does not help in burning.

45. [B]Question:[/B] Why does blotting paper absorb ink?
[B]Answer:[/B] Blotting paper has fine pores, which act like capillaries. When a portion of blotting paper is brought in contact with ink, ink enters the pores due to surface tension (capillary action f liquids) and is absorbed.

46. [B]Question:[/B] Why does a small iron sink in water but a large ship float?
[B]Answer:[/B] The weight of water displaced by an iron ball is less than its own weight, whereas water displaced by the immersed portion of a ship is equal to its weight (Archimedes? Principle).

47. [B]Question:[/B] Why does ice float on water?
[B]Answer:[/B] The weight of the ice block is equal to the weight of the liquid displaced by the immersed portion of the ice.

48. [B]Question:[/B] Why does moisture gather outside a tumbler containing cold water?
[B]Answer:[/B] The water vapour in the air condenses on cooling and appears as droplets of water.

49. [B]Question:[/B] Why does kerosene float on water?
[B]Answer:[/B] Because the density of kerosene is less than that of water. For the same reason cream rises in milk and floats at the top.

50. [B]Question:[/B] Why is the water in an open pond cool even on a hot summer day?
[B]Answer:[/B] As the water evaporates from the open surface of a pond, heat is taken away in the process, leaving the surface cool.

51. [B]Question:[/B] Why is it less difficult to cook rice or potatoes at higher altitudes?
[B]Answer:[/B] Atmospheric pressure at higher altitudes is low and boils water below 1000C. The boiling point of water is directly proportional to the pressure on its surface.

52. [B]Question:[/B] Why is it difficult to breathe at higher altitudes?
[B]Answer:[/B] Because of low air pressure at higher altitudes the quantity of air is less, and so that of oxygen.

53. [B]Question:[/B] Why are winter nights and summer nights warmer during cloudy weather than when the sky is clear?
[B]Answer:[/B] Clouds being bad conductors of heat do not permit radiation of heat from land to escape into the sky. As this heat remains in the atmosphere, the cloudy nights are warmer.

54. [B]Question:[/B] Why is a metal tyre heated before it is fixed on wooden wheels?
[B]Answer:[/B] On heating, the metal tyre expands by which its circumference also increases. This makes fixing the wheel easier and therefore cooling down shrinks it; thus fixing the tyre tightly.

55. [B]Question:[/B] Why is it easier to swim in the sea than in a river?
[B]Answer:[/B] The density of sea water is higher; hence the up thrust is more than that of river water.

56. [B]Question:[/B] Who will possibly learn swimming faster-a fat person or a thin person?
[B]Answer:[/B] The fat person displaces more water which will help him float much more freely compared to a thin person.

57. [B]Question:[/B] Why is a flash of lightening seen before thunder?
[B]Answer:[/B] Because light travels faster than sound, it reaches the earth before the sound of thunder.

58. [B]Question:[/B] Why cannot a petrol fire be extinguished by water?
[B]Answer:[/B] Water, which is heavier than petrol, slips down permitting the petrol to rise to the surface and continue to burn. Besides, the existing temperature is so high that the water poured on the fire evaporates even before it can extinguish the fire. The latter is true if a small quantity of water is poured.

59. [B]Question:[/B] Why does water remain cold in an earthen pot?
[B]Answer:[/B] There are pores in an earthen pot which allow water to percolate to the outer surface. Here evaporation of water takes place thereby producing a cooling effect.

60. [B]Question:[/B] Why do we place a wet cloth on the forehead of a patient suffering from high temperature?
[B]Answer:[/B] Because of body?s temperature, water evaporating from the wet cloth produces a cooling effect and brings the temperature down.

61. [B]Question:[/B] When a needle is placed on a small piece of blotting paper which is place on the surface of clean water, the blotting paper sinks after a few minutes but the needle floats. However, in a soap solution the needle sinks. Why?
[B]Answer:[/B] The surface tension of clean water being higher than that of a soap solution, it cans support the weight of a needle due to its surface tension. By addition of soap, the surface tension of water reduces, thereby resulting in the sinking of the needle.

62. [B]Question:[/B] To prevent multiplication of mosquitoes, it is recommended to sprinkle oil in the ponds with stagnant water. Why?
[B]Answer:[/B] Mosquitoes breed in stagnant water. The larvae of mosquitoes keep floating on the surface of water due to surface tension. However, when oil is sprinkled, the surface tension is lowered resulting in drowning and death of the larvae.

63. [B]Question:[/B] Why does oil rise on a cloth tape of an oil lamp?
[B]Answer:[/B] The pores in the cloth tape suck oil due to the capillary action of oil.

64. [B]Question:[/B] Why are ventilators in a room always made near the roof?
[B]Answer:[/B] The hot air being lighter in weight tends to rise above and escape from the ventilators at the top. This allows the cool air to come in the room to take its place.

65. [B]Question:[/B] How does ink get filled in a fountain pen?
[B]Answer:[/B] When the rubber tube of a fountain pen immersed in ink is pressed, the air inside the tube comes out and when the pressure is released the ink rushes in to fill the air space in the tube.

66. [B]Question:[/B] Why are air coolers less effective during the rainy season?
[B]Answer:[/B] During the rainy reason, the atmosphere air is saturated with moisture. Therefore, the process of evaporation of water from the moist pads of the cooler slows down thereby not cooling the air blown out from the cooler.

67. [B]Question:[/B] Why does grass gather more dew in nights than metallic objects such as stones?
[B]Answer:[/B] Grass being a good radiator enables water vapour in the air to condense on it. Moreover, grass gives out water constantly (transpiration) which appears in the form of dew because the air near grass is saturated with water vapour and slows evaporation. Dew is formed on objects which are good radiations and bad conductors.

68. [B]Question:[/B] If a lighted paper is introduced in a jar of carbon dioxide, its flame extinguishes. Why?
[B]Answer:[/B] Because carbon dioxide does not help in burning. For burning, oxygen is required

69. [B]Question:[/B] Why does the mass of an iron increase on rusting?
[B]Answer:[/B] Because rust is hydrated ferric oxide which adds to the mass of the iron rod. The process of rusting involves addition of hydrogen and oxygen elements to iron.

70. [B]Question:[/B] Why does milk curdle?
[B]Answer:[/B] Lactose (milk sugar) content of milk undergoes fermentation and changes into lactic acid which on reacting with milk protein (casein) form curd.

71. [B]Question:[/B] Why does hard water not lather soap profusely?
[B]Answer:[/B] Hard water contains sulphates and chlorides of magnesium and calcium which forms an insoluble compound with soap. Therefore, soap does not lather with hard water.

72. [B]Question:[/B] Why is it dangerous to have charcoal fire burning in a closed room?
[B]Answer:[/B] When charcoal burns it produces carbon monoxide which is suffocating and can cause death.

73. [B]Question:[/B] Why is it dangerous to sleep under trees at night?
[B]Answer:[/B] Plants respire at night and give out carbon dioxide which reduces the oxygen content of air required for breathing.

74. [B]Question:[/B] Why does ENO's salt effervesce on addition of water?
[B]Answer:[/B] It contains tartaric acid and sodium bicarbonate. On adding water, carbon dioxide is produced which when released into water causes effervescence.

75. [B]Question:[/B] Why does milk turn sour?
[B]Answer:[/B] The microbes react with milk and grow. They turn lactose into lactic acid which is sour in taste.

76. [B]Question:[/B] Why is a new quilt warmer than an old one?
[B]Answer:[/B] In a new quilt the cotton is not compressed and as such it encloses more air which is bad conductor of heat. Therefore, it does not allow heat to pass.

77. [B]Question:[/B] Curved rail tracks or curved roads are banked or raised on one side. Why?
[B]Answer:[/B] Because a fast moving train or vehicle leans inwards while taking turn and the banked or raised track provides required centripetal force to enable it to move round the curve.

78. [B]Question:[/B] How do bats fly in dark?
[B]Answer:[/B] When bats fly they produce ultrasonic sound waves which are reflected back to them from the obstacles in their way and hence they can fly without difficulty.

79. [B]Question:[/B] Water pipes often burst at hill stations on cold frosty nights. Why?
[B]Answer:[/B] The temperature may fall below 00C during cold frosty nights which converts the water inside the pipes into ice, resulting in an increase in volume. This exerts great force on the pipes and as a result, they burst.

80. [B]Question:[/B] Why are white clothes more comfortable in summer than dark or black ones?
[B]Answer:[/B] White clothes are good reflectors and bad absorbers of heat, whereas dark or black clothes are good absorbers of heat. Therefore, white clothes are more comfortable because they do not absorb heat from the sun rays.

81. [B]Question:[/B] Why does a rose appear red grass green in daylight?
[B]Answer:[/B] Rose absorbs all the constituent colors of white light except red which is reflected to us. Similarly, grass absorbs all colors except green which is reflected t us.

82. [B]Question:[/B] Why does a ship rise as it enters the sea from a river?
[B]Answer:[/B] The density of sea water is high due to impurities and salts compared to river water as a result; the upthurst produced by the sea water on the ship is more than that of river water.

83. [B]Question:[/B] Why are fuse provided in electric installations?
[B]Answer:[/B] A safety fuse is made of a wire of metal having a very low melting point. When excess current flows in, the wire gets heated, melts and breaks the circuit. By breaking the circuit it saves electric equipment or installations from damage by excessive flow of current.

e84. [B]Question:[/B] Why is it easier to lift a heavy object under water than in air?
[B]Answer:[/B] Because when a body is immersed in water, it experiences an upward thrust (Archimedes? Principle) and loses weight equal to the weight of the water displaced by its immersed potion, and hence, is easier to lift objects.

85. [B]Question:[/B] If a highly pumped up bicycle tyre is left in the hot sunlight, it bursts. Why?
[B]Answer:[/B] The air inside the tube increases in volume when heated up. As sufficient space for the expansion of the air is not available because the tube is already highly pumped, it may result in bursting of the tyre.

86. [B]Question:[/B] What will be the color of green in blue light?
[B]Answer:[/B] Grass will appear dark in color because it absorbs all other colors of the light except its own green color. The blue light falling on grass will be absorbed by it, and hence, it will appear dark in color.

87. [B]Question:[/B] Why do two eyes give better vision than one?
[B]Answer:[/B] Because two eyes do not form exactly similar images and he fusion of these two dissimilar images in the brain gives three dimensions of the stereoscopic vision.

Scientific reason
 

1.what is the biological reason due to which one should eat rice first and then roti?

2.we always see a shadow behind the moon ?what is that
is that the same cocept of phases of moon ?

3.How does a lizard form?

quote:
Detergents are better cleaning agents:
Detergents have two different ends-one water liking(hydrophobic) and the other oil liking(hydrophobic).when a dirty greasy object is placed in water containing detergent,the oil liking ends join up with the grease.the grease is then effectively coated with the water-liking endsa and therefore dissolves in the water.some dirt is muddy,in this case the detergent makes the water to wet the fabric better thereby tending to push the dirt off.Agitation helps this operation n it is provided by the washing machine.

why light coloured clothes are generally worn in summer???

[QUOTE=aneeqa;170476]why light coloured clothes are generally worn in summer???[/QUOTE]

Because dark colors absorb heat.

[QUOTE=Last Island;170484]Because dark colors absorb heat.[/QUOTE]

Well tht ll be more an answer to "Y we dont wear dark color dresses in summer" rather than "Y we use light colors in summer"

The more appropriate answer ll be coz light colors r gud reflectors of light nd hence produce less heat.
Kehnay ko its all the same but on technical grounds dere z difference

Regards

why the dead body floats?

[QUOTE=saim n babar;189562]why the dead body floats?[/QUOTE]

A dead body in the water starts to sink as soon as the air in its lungs is replaced with water. Once submerged, the body stays underwater until the bacteria in the gut and chest cavity produce enough gas—methane, hydrogen sulfide, and carbon dioxide—to float it to the surface like a balloon. At first, not all parts of the body inflate the same amount: The torso, which contains the most bacteria, bloats more than the head and limbs. The most buoyant body parts rise first, leaving the head and limbs to drag behind the chest and abdomen. Since arms, legs, and the head can only drape forward from the body, corpses tend to rotate such that the torso floats facedown, with arms and legs hanging beneath it.

why hot soup/food is more tasty than cold one?

why women dont become bald?

why right handed ppl live longer than left handed? (on average)

what are the "Life Features" of candle? on the basis of which we can call it has life like all of us?

which tree cant reproduce itself? man propagate it?

why petrol fire cant be extinguished by water?

[QUOTE=Kashinov;55221]

2# Why rainbow is produced in the sky after rainfall and sunlight?

[B]ANS: This is due to the splitting of sunlight into it's 7 basic colours: VIBGYOR.....after sunlight passes thru a raindrop and is a result of refraction.[/B]

[/QUOTE]
dear rainbow is due to reflection as well as refraction of light. light enters into drop, then reflected back rom opposite side of the drop at 42 dgree (w r t its original entry and u can only see if ur back is towards sun

why women dont become bald?

No its not so women could also get bald if they inherit it geneticly...but ys they do n,t grow compltely bald.
Reason
High levels of testosteroneand and insulin hormones make men more prone to hair loss while these hormones specially testesterone are in small quantity in females thats wyh they do n,t develop male pattern baldness.

why right handed ppl live longer than left handed? (on average)

Its just a myth......scientifically only a minute difference exists between the death incidencez of right handerz and left handrz....

why petrol fire cant be extinguished by water

Because the petrol is fluid itself, and it doesn't chemically bond well with water,thats why fire won,t be suffocated by water.


what are the "Life Features" of candle?
Like living organisms candle requires oxygen to keep burning,if deprived of air it wo n,t burn........

why some detergents include live microbes?

what shou;ld be increased to make float a drowning body? (its length, width or height) and why?

if i drop from the tower of pisa a kilo of wool and also a kilo of iron. which will hit the land first? first think then reply?

if we allow DC current to flow from electric wires what will happen? (normally AC current flows through them)

why bread become green then black? why do it not turn black then green?

why jet fighters fly in v shaped form?

why brown eyes are dominant over blue ones? and why europeans have A and asian have B blood group on average?

manual qulfi makers add salt to ice? why do they do this?

how X rays can be used to check diamond purity? how

why wax shrink on heat? (opposite to normal things)

why fire does not work on the threads of asbestos?

how infra red rays help to read from burnt papers?

can we increase the speed of light? if yes then how .plz think then reply(i dont need the ans. NO)

why can we not cut the diamonds?(normaly)

why do monkeys have tail and humans dont have?(genetically)

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[B]why some detergents include live microbes?[/B]

Microbes act on the stains and other blots biologically...for example there might be a microbe that acts of the petrol that is lost to the oceans.

[B]if i drop from the tower of pisa a kilo of wool and also a kilo of iron. which will hit the land first? first think then reply?[/B]

Both will hit the ground at exactly the same moment. (Acceleration of the earth is uniform and we can ignore the air resistance)

[B]what should be increased to make float a drowning body? (its length, width or height) and why?[/B]

it's density. that is mass per unit volume.

[B]why jet fighters fly in v shaped form?[/B]

during world war 2, this was a formation adopted by the allies which denoted V for victory.

[B]manual qulfi makers add salt to ice? why do they do this?[/B]

so that ice melts slowly and at higher temperatures. impurities increase the freezing point of any substance.

[B]why can we not cut the diamonds?(normaly)[/B]

diamonds can be cut but they are one of the hardest substances on the planet. It is because of the strong covalent bonds between the carbon atoms that constitute a diamond.

[QUOTE=umarabbas;196682]

[B]why jet fighters fly in v shaped form?[/B]

during world war 2, this was a formation adopted by the allies which denoted V for victory.[/QUOTE]

aerodynamically v shape flight of geese provide lifting power. humans just copy. here v does not stand for victory

I wanna add something that testosterone is one the causes of baldness and especially Pattern baldness in Men. ( MEDICAL PHYSIOLOGY BY GUYTON)
What's pattern baldness??? It is fall of hair on the dorsal side of forehead..it is also an assurity that the person is sexually sound.

[QUOTE=siraj narejo;196771]aerodynamically v shape flight of geese provide lifting power. humans just copy. here v does not stand for victory[/QUOTE]

Dear Siraj,

Your argument would have held if the question would have been why the wings of the planes are shaped like this....but they are asking about the flight pattern.. and geese might be using this formation for protective purposes rather than having an aerodynamic flight patttern...