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  #21  
Old Sunday, November 06, 2011
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401. Vaccine for T.B is Bacillus Calmette Guerin (BCG)

402. Mitochondria is called the power house of the cell.

403. Persons with AB+ blood group are considered to be universal recipient.

404. Study of life in outer space is known as Exobiology.

405. The name of the common mineral salt present in sweat is Sodium Chloride.

406. Sensitive layer of the eye is Retina.

407. Laughing gas as the composition of Nitrogen and Oxygen.

408. Dr. Abdus Salam of Pakistan was one of the contributors of the unification of Electromagnetic force and weak nuclear force.

409. CAT triplet in DNA codes for valine.

410. The chance of diabetic baby born to parents both heterozygous normal is ¼.

411. Inheritance of acquired characters is not an art of Darwinism.

412. Role of biotechnology in the production of food is based on Fermentation.

413. Founder of modern astronomy was Nicolas Copernicus.

414. The instrument which measures very high temperature is Pyrometer.

415. The science which deals with study of manners and customs of people is Ethics.

416. Dry ice is Solid Carbon Dioxide.

417. Chemical name of vinegar is Dilute Acetic Acid.

418. Deficiency of Pyridoxine decreases haemoglobin production.

419. Orbital period of the planet Mercury around the sun is 88 days.

420. The most splendid and the most magnificent constellation on the sky is Orion.

421. “Black holes” refer to Collapsing objects of high density.

422. Eugenics is the study of altering human beings by changing their genetic components.

423. The position of earth in its orbit when it is at its greatest distance from the sun causing northern summer is called Aphelion.

424. Ionosphere layer make the radio transmission possible.

425. Television signals are converted into light signals by Transistor.

426. Most of Asteroids lie in asteroid belt between the orbit of Mars and Jupiter.

427. The number of spark plugs needed in a diesel engine is 0.

428. The half-life of a radioactive element is 8 days. It takes 8 days to reduce it from 10mg to 5 mg.

429. The term “Blue Shift” is used to indicate Doppler Effect in which an object appears bluer when it is moving towards the observer or observer is moving toward the object.

430. Kilowatt-hour is a unit of Power.

431. Fuel used in a Fast Breeder Reactor is Uranium Plutonium Oxide.

432. Monsoon is caused by Revolution of earth.

433. Atmospheric layer ionosphere helps in radio communication.

434. A moderator is used in nuclear reactor in order to slow down the speed of the neutrons.

435. Sedimentary rocks are Porous.

436. Gypsum is a non-metallic mineral.

437. Ozone layer prevents the ultraviolet radiation from entering the atmosphere.

438. The phenomenon of Aurora Borealis, the display of red and green lights in northern hemisphere is due to radiations from Ionosphere.

439. Oasis is associated with Desert.

440. Quartz crystal in quartz watches work on the principle called Piezo-electric effect.

441. The fruits with seed, like banana, are called Parthenocarpic fruits.

442. Animal which captures and readily kills living animals for tis food is called Predator.

443. In a railway track, two rails are joined end in end with a gap in between them to avoid accidents due to expansion.

444. Al-Qanoon is the famous book of Ibn-e-Sina in which human physiology and medicine are discussed.

445. Copper can be converted into gold by Artificial Radioactivity.

446. In winter an iron pipe feel colder than a wooden window. This is because wood is non-conductor.

447. The echo (reflected sound) will be distinctly heard only at ordinary temperatures if the distance of the reflecting surfaces from the source of sound is at least 56 ft.

448. It is possible to recognize a person in the dark by simply hearing hiss unique voice. It is because of the Pitch.

449. When a ray of sunlight enters a dark room, its straight path becomes visible because of dust particles hanging in the air. It is because light is Transparent.

450. The principle used in radar is the same as that of sonar. In radar we use radio waves; whereas in sonar we use Ultrasonic.

451. Parsec is a unit of distance.

452. The German or nickel silver is composed of approximately 60% copper, 20% nickel and 20% zinc.

453. The temperature of the dead body is the temperature of the place where it is kept.

454. Cusec is the unit for measuring the flow of liquids/flow rate, equal to one cubic foot per second.

455. The deepest place on earth is Mariana trench.

456. Twinkling of stars is caused by Refraction of light.

457. Magnifying power of a simple microscope can be increased by decreasing focal length of the lens.

458. A very important practical application of properties of matter is hoeing or “godi” practiced by the farmers. This property of matter is called Capillarity.

459. It is observed that the total pressure exerted by air on the man of average size is around 14.7 lb. wt. per square inch. But the man feels quite comfortable. It is because of an equal and opposite pressure acts from inside.


460. A nuclear reactor is a device used to carry out controlled nuclear reaction whereas GM counter is a device used to detect nuclear radiation.

461. A body can escape the gravitational pull of the earth if it is thrown up with a velocity of 7 miles per sec.

462. Night vision is possible with the help of Infrared Rays.

463. Myopia is a defect of human eye. It can be corrected by using a lens called concave lens.


464. Walnuts can be broken in the hand by squeezing two together but not one. It is because of work done.

465. The instrument which is specially designed for recording earth quake wave is called seismograph which measure earth quake waves on a Richter scale.

466. Fossils found in the lowest geological strata are generally most primitive.

467. Evolution can be described as a continuing process.

468. Mutation is the only source new alleles.

469. Polygenic characteristic are controlled by Multiple Genes.

470. Digestion involves ingestion, digestion, absorption and elimination.

471. In humans, most nutrient molecules are absorbed by the small intestine.


472. The energy needed to fuel essential body processes is called Basal metabolism.

473. Inhaled air passes through Bronchiole in the last.

474. Hermaphroditism is a form of sexual reproduction.

475. Cobalt is a metal which is strongly attracted by a magnet.

476. Hepatitis A is transmitted to different individuals by Faeces.

477. The unit that coordinates different devices of the computer system is Control unit.

478. The approximate intensity level of the sound which can cause damage is 100 decibel (dB).

479. Fuse wire is made of 63% tin and 37% lead.

480. The unit of photosynthesis in green plants is called Quantosome.

481. The property by virtue of which metals can be beaten into thin sheets is known as Malleability.

482. The sky appears blue because the earth’s atmosphere Reflects blue light.

483. Gamma rays are Higher energy rays emitted by radioactive elements.

484. The radiation that is used in magnetic resonance imaging (MRI) is in the infra-red range.

485. Lead is used in storage batteries.

486. The gas produced during the fermentation of Biomass is Methane.

487. Biogas is the common name of Natural Gas.

488. Bacteria help in the process of fermentation of biomass.

489. One thousand watt power is called as 1 kilowatt.

490. The meter installed in our homes measure electricity in KWh.

491. Unis of electricity consumed by 2500 watt air-conditioner in one hour are 2.5 units.

492. Gas bills are charged in CGS and BTU.

493. In BTU system, one BTU is equal to 1055 joule.

494. Air is present in the atmosphere of earth up to the height of 200 kilometres.

495. All forms of energy that we use are ultimately transformed into Heat energy.

496. The gas which acts as a glass of greenhouse is Carbon dioxide.

497. Google is the largest search engine of internet.

498. Carbon dioxide is used in the preparation of soft drinks.

499. World’s largest flower auction is held in Aalsmeer.

500. All the plant life is based upon the compounds, which are made up of Oxygen, Carbon and Nitrogen.
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  #22  
Old Sunday, November 06, 2011
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Originally Posted by Roshan wadhwani View Post


221. Hot liquid rock beneath the earth’s surface is called Lava/Magma.

Hot liquid rock beneath the earth’s surface is called Lava
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  #23  
Old Thursday, November 10, 2011
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501. Huge white ball in the sun almost consists of Hydrogen.

502. Charcoal is made by heating wood.

503. In blood, the percentage of water is 90%.

504. As the temperature of ice rises, the ice melts and its density increases.

505. Water is a universal solvent for Biochemical Reactions.

506. The temperature of the water below the solid ice layer is 4 degree centigrade.

507. The volume percentage of nitrogen in air is 78%.

508. The composition of oxygen in air is kept constant by the process of Photosynthesis.

509. Nitrogen occurs in plants and animals in the form of Protein.

510. Air contains volume of carbon dioxide approximately 0.03%.

511. The gases which are used by divers as an artificial atmosphere are helium and oxygen.

512. Noble gases are extremely unreactive.

513. The second most abundant metal found in the earth’s crust is Iron.

514. The iron content in plant tissue is normally between 50-250ppm.

515. Chernobyl nuclear reactor lies in Russia.

516. Chernobyl nuclear plant was destroyed in 1986 due to Failure of cooling system.

517. Radioactive source must be kept in Lead Container.

518. In Brazil alcohol is used as fuel for vehicles.

519. Voltmeter can be made by modification in Galvanometer.

520. The device used for the measurement of current, voltage and resistance is AVO meter.

521. In the name of multimeter “AVO”, V stands for Voltage.

522. Silicon is a Semiconductor.

523. Paper is an insulator.

524. For sending sound waves at large distance, Radio Waves are used.

525. The carrier waves used for the radio transmission have the frequency up to 30 KHz.

526. Video camera is used to convert Picture into electrical signals.

527. In a colour television, the colours are green, red and blue.

528. The waves used for sending signals to the satellite from ground station are Micro Waves.

529. First telegraph signal was transmitted in 1901.

530. In a telephone receiver, Magnet is placed under the diaphragm.

531. Nowadays, the international communication and transmission is being done through the waves known as Microwaves.

532. Modern Bicycle was invented by Staley.

533. Coulomb is the unit of Electric Charge.

534. For certain reasons, some people develop cloudy areas in one or both lenses. This defect is called Cataract.

535. In order to prevent the corrosion of iron pipes they are often coated with a layer of zinc. This process is termed as Galvanization.

536. In a reactor, cadmium rods re used for Absorbing Neutrons.

537. Detergents dissolved in water help in cleaning clothes by reducing the surface tension of water.

538. The swing of a spinning cricket ball in the air can be explained on the basis of Bemoulli’s Theorem.

539. The absorption of ink by blotting paper involves Capillary Action phenomenon.

540. Materials for rain proof coats and tents owe their water proof properties to Surface Tension.

541. For being able to see three-dimensional pictures we have to use An Epidiascope.

542. Water has maximum density at 4 degree centigrade.

543. The highest recorded air temperature in the world in degree Celsius is 57.

544. The instrument that measures wind speed is the anemometer.

545. The theory of expanding Universe was first propounded by Hubble.

546. Used tea leaves contain Quinine.

547. A lake starts freezing because of the cold atmosphere. It will first freeze at the top surface.

548. The Sun remains visible for some time after it actually sets below the horizon. This happens due to Atmospheric Refraction.

549. An iceberg is floating in sea. One tenth of its mass will remain above the surface of water.

550. Bat has the highest upper limit of audible range.

551. “Hotline” is A telecommunication link between the rulers of countries.

552. Most of the ozone is concentrated in the Stratosphere.

553. The cow’s milk contains 80% of water in terms of percentage.

554. Numismatics is the study of Coins.

555. Measles is a viral disease.

556. Vitamin C is present in Citrus Fruits.

557. Leukaemia is a Blood Cancer.

558. Haemophilia is a hereditary disease.

559. Diamond is the hardest material.

560. Lead ball falls through water more slowly than through air because of the viscous force in water.

561. Polaroid’s are used for Photoelasticity.

562. Scalding with steam is more severe than scalding by boiling water because Steam contains more energy than boiling water.

563. Cooking oil can be converted into vegetable ghee by the process of Hydrogenation.

564. Stainless steel is an alloy of Iron, Chromium and Nickel.

565. Optical fibres work on the principle of Total internal reflection.

566. Water vapour beyond the dew point results in Condensation.

567. The main chemical substance present in the bones and teeth of animals is Calcium Phosphate.

568. The Green House Effect is caused by an excess of Carbon dioxide.

569. Bats can also fly in dark because they are capable of taking the help of Ultrasonic Waves.

570. Gold is found in its original form.

571. Green vegetables have high iron content.

572. The fat content in buffalo milk is 10%.

573. Whale has the largest egg.

574. The rear view mirror of a motor vehicle is Convex.

575. A post mortem study usually involves an analysis of liver.

576. Bio fertilisers are nitrogen-fixing micro-organisms which can enrich soil.

577. Tincture of iodine consists of A solution of iodine in alcohol.

578. The only planet of solar system which has water vapours is Neptune.

579. The major part of natural gas, petroleum and coal consist of Methane.

580. Gypsum is used for cement.

581. Chromium is obtained from Chromite.

582. Silica is used in glass-making.

583. Human population has become double during the last 45 years.

584. At present population growth rate in Pakistan is 1.573%.

585. In Pakistan, the nuclear power stations are built at Karachi and Chashma.


586. Plutonium is used as Fuel for nuclear fission.

587. Uranium-235 is used in the fission process.

588. The solar energy falling on the atmosphere of earth is almost 1.4 kilowatt per square meter.

589. The large plates of solar panels are painted Black.

590. The temperature of the semi-molten rocks about 10 km below the surface is 200 degree Centigrade.

591. Cataract is a disease of eye.

592. Rayon is made of Cellulose.

593. Meter per second is a unit of Velocity.

594. The greatest number of compounds is formed by the element of Carbon.

595. The major component of honey is Glucose.

596. The working principle of a washing machine is Centrifugation.

597. Oxygen is present in the largest amount in terms of per cent by mass in the earth’s crust.

598. Radioactivity was first discovered by Henry Becquerel.

599. Helium gas is commonly used in balloons and airships.

600. The process of elimination of water from any system is called Dehydration.

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  #24  
Old Thursday, November 10, 2011
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Quote:
Originally Posted by Afshan Choudary View Post
Hot liquid rock beneath the earth’s surface is called Lava
both of you are wrong dear.

when it is inside the earth it is called MAGMA,but when it come out of earth crust it is called LAVA.
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Old Thursday, November 10, 2011
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Good efforts..
>The second most abundant metal found in earth's crust is silicon. Here is the sequence of 9 elements which account for most of the matter found in earth's crust:
oxygen, silicon, aluminium, iron, calcium, sodium, potassium, magnesium, and hydrogen. out of them the non-metal elements are oxygen and hydrogen.

>Charcoal is made by animals' bones.

>when ice melts its density decreases. because density is a mass per unit area(volume). water in ice state has contracted volume and its mass per area is greater but when it melts it starts to expand, thereby its mass per unit area decrease.

Last edited by Shooting Star; Tuesday, May 15, 2012 at 02:37 AM. Reason: merged
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  #26  
Old Thursday, November 10, 2011
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601. Sparkling red colour after the blast of fire cracker is due to the presence of Sulphur.

602. The chemical name of aspirin is Acetylsalicylic acid.

603. Animal fat has the highest calories per gram.

604. The commonly present element in the artificial fertilizer is Potassium, Nitrogen and Phosphorus.

605. Potassium nitrate is used in fertilizers.

606. The inherited traits of a person can be investigated by the study of Deoxyribonucleic acid.

607. Silicon is extensively used in electronics.

608. When a bullet is fired upwards vertically, it gains in Potential energy.

609. The mixture of Acetylene and oxygen gases is required in gas welding.

610. Isobars are the lines connecting the places having same Atmospheric pressure.

611. The velocity of wind is related to Pressure gradient.

612. The acid present in the sour milk is Formic acid.

613. The most important stimulant in tea leaves is Caffeine.

614. Dolly was the name of first cloned sheep.

615. The smallest living cell is that of a Mycoplasma (bacterium)

616. We lose consciousness if blood flow to the brain is cut off more than 5 sec.

617. Menopause usually occurs between 40 to 45 years.

618. Platypus and Echidnas are the only monotremes, or mammals that lay eggs.

619. Film is that part of camera which is analogue to the retina in the human eye.

620. 72-80 is the average adult pulse rate.

621. Magnetic resonance is the modern tool for imaging brain tumours.

622. The acid used in a car battery is sulphuric acid.

623. After drinking contaminated water, you would be most apt to develop symptoms of Typhoid fever.

624. In eye donation, Cornea of donor’s eye is utilized.

625. Alzheimer is a disease of Brain.

626. Cell was discovered by Robert Hooke.

627. A body is taken from Earth to Moon. Its weight will Decreases.

628. Brass is an alloy of Copper and Zinc.

629. Mineral essential for the coagulation of blood is Magnesium.

630. Milk is an example of Emulsion.

631. Iron is the most abundant transition metal.

632. Hydrometer is used to determine specific gravity of liquids.

633. Convex lenses are used for the correction of Long-sightedness (Hyperopia)

634. A transformer is used to Increase or decrease AC voltage.

635. The stones formed in human kidney consist mostly of Calcium oxalate.

636. Most of the explosions in mines occur due to the mixing of Methane with air.

637. A mobile phone sends and receives messages through Radio waves.

638. Fax machine receives the signal and give its output through the Printer.

639. The procedure of crushing the gallstone and kidney stone by laser is called Lithotripsy.

640. Laser is used to produce an image of One dimension.

641. Three dimensional image formed by laser is called Photograph.

642. The first laser ever used is Semiconductor laser.

643. Ordinary light spreads in all directions.

644. Optical fibres are the fine strands of Glass.

645. The satellites which revolve in such an orbit, so that they move with earth rotation are called Geo-stationary satellites.

646. The elements which emit radiations have atomic number greater than 82.

647. In a normal healthy body, the number of red cells or erythrocytes in each cubic millimetre of blood is 5.0 m.

648. The average life of a red blood cell in the body is about 120 days.

649. DNA is a class of nucleic acids.

650. Cellulose is a Carbohydrate.

651. After long periods of use, a gray spot develops on the inside of a bulb. This is because the tungsten filament evaporates and collects there.

652. Ice cubes are added to a glass of pure water and a glass of a pure alcohol. The ice would be Floating in alcohol and sinking in water.

653. Protein which renders a cell less susceptible to attack by viruses is called Chloromycetin.

654. The pigment involved in photosynthesis activity is called Chlorophyll.

655. The chemical part of the dye that absorbs light and produces colour is called photo chrome.

656. A nuclear reactor harnesses nuclear energy by Controlled chain reaction.


657. Eyes are tested by dilating the pupils with a very dilute solution of Atropine.

658. Phenol is used as a raw material in the manufacture of foam used in mattresses, cushions, etc.

659. ECG is an instrument used for the disorder of Heart.

660. Carbon-14 is used for dating very old objects of archaeological importance.

661. Lead is used in storage batteries.

662. Enzymes are Biological catalysts.

663. DNA finger-printing is the latest technology used in Forensic science.

664. Potassium is used in the preparation of glass and soap in the form of Carbonates.

665. Potassium phosphate is used in the preparation of detergent.

666. In Chlorophyll, magnesium is present.

667. Calcium plays a vital role in blood clotting.

668. For water purification, Chlorine is used.

669. Deficiency of calcium causes the impaired growth in infants.

670. Wheat, rice, corn and maize are the best sources of carbohydrates.

671. The human blood is divided into four groups.

672. The muscles, tissues and blood all are made up of Proteins.

673. Iron is a part of haemoglobin which transports oxygen.

674. In thyroid glands iodine is required for the synthesis of Thyroxin.

675. The amount of calories provided by egg is 150 K calories/100gm.

676. Jupiter is the largest planet of solar system.

677. The mirror placed near the driver of a bus is Concave mirror.

678. X-rays are used to disintegrate bladder stones.

679. The percentage of carbohydrates in the normal daily food calorie requirement of an adult is about 59%.

680. Impure blood is received in the heart in the right auricle.

681. Plants take nitrogen in the form of Nitrate.

682. Washing soda in water behaves acidic.

683. The glad which maintains body temperature is the Pituitary gland.

684. Peeled banana under normal condition is brittle.

685. Phrenology deals with sensory perception of animals.

686. Vinegar is produced by two steps, first fermentation of sugar by yeast, second fermentation of ethyl alcohol by bacteria.

687. The longest and the strongest bone in the human body is Femur.

688. Red color has the longest wavelength and violet has the shortest wavelength.

689. Chronometer is used to measure Time.

690. Carbon dioxide is used in fire extinguishers.

691. Hereditary disorders are the result of Defective DNA nucleus.

692. Pure gold is 24 carat.

693. One horse power is equal to 746 watts.

694. Dynamo is a device that converts Mechanical energy into electrical energy.

695. The minimum velocity required to escape from the gravitational pull is 11.2 km/s.


696. Heavy water consists of Oxygen and heavy hydrogen.

697. Polio is a viral disease.

698. Ag is the symbol for silver.

699. Babbage is called the father of computer.

700. Dead red blood cells are stored in liver.
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Old Friday, November 11, 2011
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Quote:
Originally Posted by shakeel ghori View Post
Good efforts..
>The second most abundant metal found in earth's crust is silicon. Here is the sequence of 9 elements which account for most of the matter found in earth's crust:
oxygen, silicon, aluminium, iron, calcium, sodium, potassium, magnesium, and hydrogen. out of them the non-metal elements are oxygen and hydrogen.

>Charcoal is made by animals' bones.

corrected answers :-


1) Element Abundance Abundance
(percent by weight) (parts per million by weight)
Oxygen
46.1% , 461,000
Silicon
28.2% , 282,000
Aluminum
8.23% , 82,300
Iron
5.63% , 56,300
Calcium
4.15% , 41,500
Sodium
2.36% , 23,600
Magnesium
2.33% , 23,300
Potassium
2.09% , 20,900
Titanium
0.565% , 5,650
Hydrogen
0.14% , 1,400



2)One of the most common forms of carbon is charcoal. Charcoal is made by heating wood in the absence of air so it does not catch fire. Instead, it gives off water vapor, leaving pure carbon.


3)

• Water is the only substance in nature that has lower density on its solid state. This happens because air is trapped in betwen the molecules of water when they freeze and make it expand. This is the reason water is so importat for lifeforms to appear on planets
• The density of water increases until 4 degrees Celsius at which point it starts to decrease. As a result, ice is lighter and will float on water. When ice melts its temperature rises to the 4 degree point and it starts to sink into the surrounding water. Density is connected to state so solids are denser than liquids which are denser than gases.

Density= Mass/Volume. When water freezes, its volume increases. This is why a frozen bottle of water expands to the point of bursting. By the formula, if volume increases and Mass stays the same, then the value of density decreases. Thus, this is why ice floats and is less dense than water. When the ice melts, the reverse happens in that its volume decreases and again by the formula, density will increase.

corrections are most welcome.
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701. Spring tides occur on new moon and full moon days because on these days Sun, moon and earth are in a straight line.

702. Clayey soil is best suited for cotton.

703. The time interval between two beats of a normal human heart is 1 second.

704. The material used for bleaching paper pulp is Sodium hypochlorite.

705. Mercury has the smallest diameter.

706. The instrument, used for recording tremors of earth, is known as Seismograph.

707. Ionosphere makes the radio transmission possible.

708. Colour of the skin is due to the presence of Melanin.

709. Natural rubber is a protein.

710. Concave mirror can be used to focus sunlight.

711. Liver secrets bile.

712. When an object is transferred from the earth to the moon its mass remains unchanged.

713. The unit of sound is Decibel.

714. It is economical to transmit electric power at high voltage.

715. Diamond does not have a tetrahedral structure.

716. The unit to measure the supersonic speed is Mach.

717. The application of the principles of genetics to the improvement of human race is known as Eugenics.

718. The penetration of x-rays through an object depends upon the object’s Density.

719. Using Ultrasound, we can determine the Structure of the body.

720. The find the hidden secrets under the water, the ships and submarines use the Sonar system.

721. The dirt in the dirty water can be separated by using the Ultrasound.

722. Recording of brain waves from outer surface of head is called E.E.G (Electroencephalograph).

723. The first rocket launched by Pakistan was Rahber.

724. The first Nuclear power plant in Pakistan was established at Karachi.

725. Sodium benzoate is used for preservation of food grains.

726. Steel is more elastic than rubber because ratio of stress to strain is more.

727. Haemoglobin makes the blood look red.

728. Mercury is extracted from Cinnabar.

729. Cattle-bone powder is used as fertilizer as it is rich in Phosphorous.

730. Heating element of an electric heater Nichrome.

731. Dry sand appears bright while wet sand appears dark because of Reflection.

732. Acid rain contains high levels of Sulphuric acid.

733. A woman’s voice is shriller than a man’s due to smaller vocal chords.

734. The blood glucose level is commonly expressed as Milligram per decilitre.

735. Soft drinks such as colas contain significant quantities of Caffeine.

736. A small pouch containing silica gel is often found in bottles of medicine in tablet or powder form because silica gel absorbs moisture.

737. Fluorescent tubes are fitted with a choke. The choke coil reduces current in the circuit.

738. For reproduction of sound, a CD (Compact Device) audio player uses a Laser beam.

739. When a CD (Compact Disc used in audio and video systems) is seen in sunlight, rainbow like colours are seen. This can be explained on the basis of the phenomenon of Reflection and diffraction.

740. If a U-238 nucleus splits into two identical parts, the two nuclei so produced will be Radioactive.

741. The total genetic material within an individual is known as the Genome.

742. The part of the body directly affected by Pneumonia is Respiratory system.

743. As the amount of clay in a soil increases, its water retaining capacity increases.

744. “O” blood group of human beings is a universal donor.

745. Amino acids are a product of the digestion of Protein.

746. Ptyalin is a starch digeting enzyme.

747. Pepsin, a digestive enzyme, is produced in the Stomach.

748. Milk is nearly a complete food by itself.

749. The acids turn the blue litmus paper Red.

750. Permanent magnets can be made from Cobalt.

751. Nights are cooler in the deserts than in the plants because Sand absorbs heat more quickly than the earth.

752. Atmospheric pressure exerted on the earth is due to the Gravitational pull.

753. Fertilizer having high nitrogen content is Urea.

754. Potassium Carbonate is used for removing air bubbles from the glass during its manufacture.

755. The chemical name for “baking soda” is Sodium Bicarbonate.

756. The snow on the mountains does not melt all at once when it is heated by the sun because it reflects most of the heat from the sun.

757. First time AIDS was identified in 1983.

758. Anthrax is a bacterial disease.

759. Blood is formed in bone marrow in human body.

760. Quark is the smallest part of the matter discovered by the scientists.

761. Trachoma is a disease of the eye.

762. The heart of a normal adult human being weighs about 300 grams and that of woman 200 grams.

763. Heart pumps 5 litre blood per minute in a normal human adult (at resting position).

764. The part of the body directly affected by Rikets is bone tissue.

765. Histology is the study of tissues.
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SCIENTIFIC REASONS FROM PAST PAPERS (95 To 2011):


1) The Earth bulges out at equator. Why?

Ans: This is due to the shape of the earth. The earth is not a true sphere but it is an ellipsoid. The equatorial diameter of the earth is 12756.27 kms. While its polar diameter is 12713.505 km. the difference between its equatorial and polar diameter is about 43 kilometres. The rotation of the earth on its axis produces a centrifugal force which increases its equatorial diameter. That is why earth bulges at the equator.

2) The Sun appears red at sunset and sunrise. Why?

Ans: The sun appears red at the time of sunset and sunrise due to the scattering of light by small particles of dust or smoke near the surface of the earth. The light travels relatively without hindrance that is why the sun appears red at the time of sunset and sunrise.

3) The ozone layer in the atmosphere is necessary for our survival. Why?

Ans: ozone layer in the atmosphere is very necessary for plant and animal survival because it is the absorber of ultraviolet rays which are very dangerous for animal health. Ultraviolet rays cause cancer of skin, spotting of plants etc. that is why the ozone layer is necessary and essential for animal as well as plant survival.

4) The sky from moon appears black. Why?

Ans: as the moon has no atmosphere, so the sky looks completely black when viewed from the moon.

5) Roads are bent inwards on curves. Why?

Ans: The roads are bent inwards on the curves and at the turns because the bents avoid falling outside and prevent the accidents.
OR
When an object turns in a circle it is influenced by a centrifugal force which pushes it away from the centre of the circle. When vehicles turn on a road they fall outside under the influence of centrifugal force. In this way there is danger of falling or slipping out of road at a turn. Roads are made in a way that these bent inward at the turns to avoid falling outside and to prevent accidents.

6) Australian continent has winter season when we have summer season in Pakistan.

Ans: the earth on its axis is not at a vertical angle to its orbit. It is inclined at an angle of about. In this way when the northern hemisphere of the earth is inclined to the sun and getting direct sun rays, southern hemisphere is inclined away from the sun and getting less direct rays. Thus the northern hemisphere has summer season and southern hemisphere has winter season. Pakistan is in the northern hemisphere while Australia is in the southern hemisphere. So when there is winter in Australia there is summer season in Pakistan.

7) Meat takes longer to cook on mountains.

Ans: The meat takes longer time to cook on the mountains because the atmospheric pressure decreases with attitude and the boiling point of a liquid is directly proportional to the atmospheric pressure.

8) Water remains cool in earthen pitcher.

Ans: This occurs due to the process of evaporation. Water gets cooled on evaporation. As the earthenware pitcher is concerned, they have small pores. Water tends to come out of pores and evaporates which results in cooling effect on the earthenware and water.
While in the metal pots there are no pores and evaporation does not take place. Besides metal has tendency to absorb heat that why water does not get cooled in a metal pot.

9) Ice and salt mixture is used as a freezing agent by manual ice-cream makers.

Ans: In manual ice-cream making a mixture of salt and ice is always used because salt has capacity to reduce the temperature of ice by decreasing its freezing point. That’s why ice and salt mixture is used as freezing agent in manual ice cream making.

10) It is not advisable to sleep under trees during the night.

Ans: During night the plants release carbon dioxide (CO2) which is a poisonous gas and injurious to health. That is why it is not advisable to sleep under trees during night.

11) Why the green house operators paint their glass roofs white in summer?

Ans: White colour is the reflector of light and it absorbs less heat as compared to other colours. As in summer there is already very hot season and heat is not required to that level. That is why the green-house operators paint glass roofs white in summer season.

12) Water boils quicker on mountains.

Ans: On Mountains the pressure of the air is low due to height, as the air pressure decreases with altitude. In this way, water boils quicker on mountains at temperature less than 100 degree centigrade, which is the boiling point of water at ground level.

13) Rainbow is produced in the sky after rainfall and sunlight.

Ans: After rain, many droplet of water travel in the atmosphere. When sun rays fall on these droplets, dispersion of water occurs and droplets act as prism and produce a spectrum of seven colours. That’s why a rainbow is seen in the sky after rain.

14) Milk is considered as an ideal food.

Ans: Milk is considered as an ideal food due to following reasons:
a) It contains all constitute of balanced diet.
b) Milk contains fat.
c) Milk has high nutritional value because it contains proteins as well as minerals.

15) Lunar eclipse last much longer than solar eclipse.

Ans: 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.

16) Goitre is common in hilly areas.

Ans: Goitre is common in hilly areas because there is deficiency of Iodine in the water.

17) Detergents are better cleaning agents.

Ans: A detergent consists of hydrophilic and hydrophobic ends. In case of dirt the detergent pushes the dirt off the wet surface of the fabric. The washing machine provides the agitation.

18) Decomposers are important for life.

Ans: Decomposers break down animal waste and dead organisms in order to get energy and release free nutrients back into the ecosystem.
OR
Decomposers break down organics into nutrients, which can be used by living organisms to create new life.

19) Places near sea are cooler in summer.

Ans: Sea water keeps the temperature moderate. In the summer season the places located near sea are cooler due to the lower temperature of water.

20) Colour blindness is more common in men than women.

Ans: Women have the sex chromosomes XX, while men have the chromosomes XY. The gene for normal colour vision is found on the X-chromosome. If a woman has one X-chromosome with the gene and one without it, she will not be colour blind. On the other hand, a man with an X-chromosome that is missing the gene has no 'backup'. He will definitely be colour blind. Colour blind women have both X-chromosomes missing the colour vision gene. This is less probable mathematically than having just one X-chromosome missing the gene.

21) Light colours absorb less heat therefore these are not heated as much as the black colour.

Ans: Dark colours do not exactly absorb more heat, but they do convert a higher percentage of light into heat. In the sun with a dark coloured shirt it gets hot, where a lighter coloured shirt would not get nearly as hot. This is due to the amount of light being absorbed by the colour. The lighter the colour the smaller is the range of visible light being absorbed and converted into heat. White objects reflect all visible light, where black objects absorb all visible light.


22) Rain water is more fertile than water from tube well.

Ans: Rain water is more fertile because it contains many salts and nitrogen dissolved from the atmosphere.

23) The manhole covers are generally round.

Ans: 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.

24) Clothes of a moving dancer bulge.

Ans: The clothes of a moving dancer bulge outside due to the centrifugal force which tends to move away from the centre.

25) People are advised not to stand near fast moving train.

Ans: One should not stand beside a fast moving train because of the strong pressure of air which carries along. A man can fall in this pressure.

26) The image of a tree is inverted on the bank of a lake.

Ans: The water of lake acts as a mirror. According to the laws of light, mirror forms inverted images.

27) Polar star is always seen in the north.

Ans: It is because the Polar Star (North Star) is closest to the location of the celestial North Pole.

28) We never see birds urinating.

Ans: The birds do not have a urinary system like other living beings which possess urinary excretory organs. In the birds the urine is excreted from body without special organs.

29) Pasteurized milk has more nourishment than the ordinary boiled milk.

Ans: Pasteurized milk is obtained by heating milk at a temperature of 60 degree Celsius for 30 minutes. In this way the TB bacteria are killed without damaging the milk protein. Thus pasteurized milk has more nourishment than ordinary boiled milk.

30) Bees die when they sting human being.

Ans: Their stingers are actually ovipositors, tubular structures extending from the abdomen that sometimes contain eggs. When the barbed stinger is left inside the victim, the honeybee mortally tears her abdomen in the process. They leave their stingers in the wound with a tiny venom sac attached. Fortunately, only about one out of a hundred people are allergic to bee sting, but allergic reactions can be very serious.

31) Cloudy nights are usually warmer than the clear ones.

Ans: The clouds serve as a barrier and prevent the loss of heat. Thus the warm temperature is maintained.

32) Why do some people snore?

Ans: Some people snore during their sleep because the breathing action produces sound. This is so because the pharynx or the windpipe offers resistance to the air taken in or expelled.

33) Why do we sometimes sleep walk?

Ans: Sleep walk is a sort of disorder of sleep in which a person starts walking during his sleep. The sleeper walks and performs complex activities automatically without regaining consciousness.

34) Climbers bend forward while climbing mountain.

Ans: While climbing a mountain, a climber bends his body forward in order to keep the centre of gravity of his body within two thirds portion. According to this principle the Pisa Tower is not falling.

35) Why climbers get their food by climbing on other trees?

Ans: The climbers are mostly parasites and they cannot manufacture their food. Therefore, they climb on other trees and get food from them.

36) Mars is called red planet.

Ans: Mars is called the red planet because its colour is red due to the desert like surface.

37) Vitamin D is the essential component of the body.

Ans: Vitamin D is necessary for body because it is essential for bone formation and retention of calcium in the human body. Vitamin D also protects the teeth.

38) The weight of the object is less at the equator than at the poles.

Ans: The weight of an object is the product of mass and force of gravity. The equatorial diameter is more than the polar diameter. Thus, the force of gravity is more at the poles and the weight is more there.


39) The dogs pant, the birds open their mouth and the elephants move rapidly their ears.

Ans: All of them do not sweat; they use the above mentioned mechanisms to cool themselves.


40) A geostationary satellite appears standstill to a viewer on the equator of earth.

Ans: Because the distance remains the same.

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More Scientific Reasons


41) Why do the stars twinkle?
Ans: The light from the stars travels through different layers of space of varying densities. Therefore, the light rays deviate from their original path. Further, these layers are not stationary but keep on moving. This leads to the twinkling of stars.

42) On what days do we have equal days and nights all over the world? And why?
Ans: On 23 September and 21 March we have equal days and nights all over the world. This is so because on these days, the rays of the sun fall vertically on the equator at noon. Both the poles receive equal rays of the sun. As a result, exactly one-half of each hemisphere receives the sun’s rays. This makes day and night equal.

43) Every fourth year has 366 days. Explain.
Ans: One revolution of the earth around the sun takes 356 days and 6 hours. But we consider a year as consisting of only 365 days and ignore 6 hours. In four years the difference becomes as much as 24 hours or one day. Hence, to every fourth year we add one day. That year of 366 days is known as leap year.

44) Why are igneous rocks called primary or parent rocks?
Ans: Igneous rocks are formed when the molten material from volcanoes gets solidified. This material is liquid, hot and sticky which moves towards the surface through cracks and joints. All other rocks derived from these rocks. Hence, they are called primary or parent rocks.

45) Why are the areas lying between the Arctic Circle and the North Pole in the Northern Hemisphere and the Antarctic Circle and the South Pole in the Southern Hemisphere very cold?
Ans: These areas are very cold because the sun does not rise much above the horizon. Therefore, its rays are always very slanting which emit minimum heat. These areas being very cold are called Frigid Zones.

46) Why are the three hot regions of the world-equatorial forests, savannah lands and hot deserts-not found in Europe?
Ans: The three hot regions of the world-equatorial forests, savannah lands and hot deserts-are not found in Europe because Europe is the only inhabited continent situated entirely outside the tropics.

47) Why is the lowest layer of the atmosphere in contact with the earth’s surface, the warmest?
Ans: The lowest layer of the atmosphere in contact with the earth’s surface is the warmest because the atmosphere is heated mainly from the below.

48) Why does the temperature above the ocean and land masses vary even on the same latitude?
Ans: Temperature above the oceans and land masses varies even on the same latitude because of the differential heating of land and water, i.e., land mass is heated and cooled more rapidly and to a greater degree than water.

49) Why are marine animals able to live at great depths than marine plants?
Ans: As marine animals do not depend upon sunlight for their survival, they are able to live at great depths where there is permanent darkness.

50) Why do trees of coniferous forests possess needle-like leaves?
Ans: The needle-like leaves limit transpiration and thus enable conifers to grow in the drier areas.

51) Why do equatorial forests appear evergreen?
Ans: In equatorial forests trees often shed a few leaves or shed their leaves seasonally, but most of the trees retain their leaves for most of the time so that the forests appear evergreen.

52) Why is petroleum often called black gold?
Ans: Petroleum is often called black gold because of its great demand in the modern industry and for domestic use. It provides fuel for heat and lighting, lubricant for machinery and raw material for a number of industries.

53) Why are the kangaroos called marsupials?
Ans: Marsupial means broad-pouch. Since kangaroos have a pouch-like fold of skin near the stomach in which they carry their young ones, they are called marsupials.

54) Why is platypus considered a strange animal?
Ans: Platypus is a strange animal because it is an animal-bird that survives under water, walks on the ground and digs tunnel under the ground. It is a four-legged animal that lays eggs like a bird. It is found in Australia.

55) Why is a person in moving vehicle thrown forward when the vehicle stops suddenly?
Ans: A person in a moving vehicle is in a state of motion. When the vehicle suddenly stops his body tends to remain in a state of motion due to inertia and he is thrown forward.

56) Earth is continuously pulling moon towards its centre. Why does not the moon fall on to the earth?
Ans: it is so because the gravitational attraction of the earth provides the necessary centripetal force to the moon for its orbital motion around the earth due to which the moon is revolving around the earth.

57) Which of the two-glass or rubber is more elastic and why?
Ans: Glass is more elastic than rubber because for a given applied force per unit area, the strain produced in glass is much more than that produced in rubber.

58) Animal like camel can easily walk in the desert sand while other animals like donkeys, dogs and horses cannot. Explain.
Ans: The camel has very broad and large feet. As a result of the large surface area in contact with the ground, it exerts less pressure on the sand and sinks only slightly in it. Other animals have smaller feet which exert more pressure on the sand. As a result, they sink more in the sand and cannot walk easily in desert.

59) Why does a small quantity of liquid assume spherical form?
Ans: A small quantity of liquid assumes a spherical form due to surface tension which tends to reduce the surface area. A given mass will acquire minimum surface area if it assumes a spherical shape.

60) Why does an iron needle float on clean water but sink when some detergent is added to this water?
Ans: Due to surface tension, the free surface of liquid at rest behaves like a stretched membrane. When an iron needle floats on the surface of clean water, its weight is supported by the stretched membrane. When some detergent is added to this water, its surface tension decreases. As a result of it, the stretched membrane on the surface of water is weakened and is not able to support the weight of needle. Hence the needle sinks in such water.

61) Why is cooking quicker in a pressure cooker?
Ans: The boiling point of water depends upon the pressure on its surface. Steam produced inside the cooker builds up pressure thereby raising the boiling point of water, which results in quick cooking.

62) Why does steam cause more severe burns than boiling water?
Ans: The amount of heat (latent heat) possessed by steam is much greater than the amount of heat possessed by water at the same temperature. Therefore, steam causes more severe burns than boiling water.

63) Why does ice not melt readily when salt is sprinkled over it?
Ans: When salt is sprinkled over ice, some of it dissolves. As dissolution of the salt is accompanied by absorption oh heat. The temperature of the system falls below 0 degree Celsius. Hence, ice does not melt readily.

64) It is difficult for firemen to hold a hose, which ejects large amount of water at a high velocity. Why?
Ans: the water which comes out of the fireman’s hose carries large momentum as its velocity is very high. The equal and opposite reaction force pushes the fireman backwards with a great speed satisfying the law of conservation of momentum. As a result, it is difficult for the fireman to hold the hose.

65) In the outer space astronauts talk to each other through radios. Why?
Ans: sound waves need a material medium for its propagation. There is no air in space and hence, sound waves cannot travel. However, radio waves can travel through space. The astronauts can see each other because light, like radio waves, can travel through vacuum.

66) Sonar scanners are used by doctors. Explain.
Ans: sonar scanners send out ultrasonic waves, which are reflected by body tissue and organs. From the pattern of reflections, a computer can build up an image of the internal structure which is vital for diagnosis.

67) Why the flash of lightning is seen before the sound of thunder is heard?
Ans: the velocity of light is much greater than that of the sound. Therefore, flash of lightning is seen before the sound of thunder is heard.

68) Bats have poor eyesight but are able to home their prey with great accuracy. Also, dolphins can avoid fishing nets and can detect fish at night. Explain
Ans: Bats emit high frequency (1, 20,000 Hz) sound waves and listen with their sensitive ears for any echoes. From the time taken to hear the echo and from the nature of sound received. Bats are able to estimate the distance and the type of surroundings. This process is known as echolocation. Same process is used by the dolphins.

69) When low flying aircraft passes overhead, we sometimes notice a slight disturbance on our TV screen. Why is it so?
Ans: a low flying aircraft reflects TV signal. Due to the interference between the direct signal and the reflected signal, there is disturbance on the TV screen.

70) In automobiles, why are convex mirrors used to see the traffic from behind?
Ans: Convex mirrors are used in automobiles because they form erect and diminished images of the object. Thus, it helps the drivers to get a wider field of view of the traffic coming from behind.

71) Why is mirage formes in the deserts?
Ans: A mirage is formed owing to total internal reflection. To the observer at a distance, the reflected image of the object appears behind the reflecting surface, as if the object were in front of it, but actually it is just an illusion.

72) What will be the colour of grass in blue light?
Ans: Grass will appear blackish in colour in blue light because it has the property of absorbing all other colours except its own colour. The blue rays falling on grass will be absorbed by it, and it will appear dark coloured.

73) A bird perches on a bare high power line and nothing happens to it. A man standing on the ground touches the same line and gets a fatal shock. Why?
Ans: When bird perches on a live high power line, no current passes through the body of bird because there is no potential difference between live wire and the body of bird as the potential of bird’s body is the same as that of wire.
When a man standing on the ground touches the same wire then due to a large potential difference between his hands and feet, a large current flows through his body to the earth.

74) During lightning it is safest to be inside a car rather than under a tree or in the open. Give reason.
Ans: When a person is in the open or under the tree, the lightning passes through his body to the earth. On the other hand, for a person inside a car, the car provider shielding and the electric field inside the car is zero, thus lightning does not affect the person inside it. The lightning actually passes through the metallic body of the car to the earth without affecting the person sitting inside it.

75) Why is earthing desirable for electric appliances?
Ans: Earthing helps the current move into the earth in the event of short-circuit, without giving a shock to the user.

76) Why does a perspiring man feel relief when air flows by his side?
Ans: The air flowing by the side of a perspiring man quickens the pace of evaporation of perspiration from the body of that person, and the resultant loss of heat from his body causes the cooling sensation which provides relief to him.

77) Why is magnet always made of soft iron?
Ans: Magnet is always made of soft iron because ‘magnetisation’ and ‘demagnetisation’ both are possible in soft iron.

78) Why are telephone wires between two poles kept loose?
Ans: Telephone wires are kept loose between two poles so that they are protected from being broken due to expansion and contraction caused by the change of temperature in summers and winters.

79) X-rays penetrate through the flesh but not through bones. Why?
Ans: The penetrating power of X-rays depends upon the potential difference between the cathode and the anode of X-ray tube. The X-rays produced can penetrate through light element like flesh of human body but they are unable to penetrate through heavier elements like bones.

80) What is a black hole? Why is it called so?
Ans: A black hole is a super dense planetary material formed due to the death of a star of mass more than five solar masses.
It is called black hole because any particle or photon approaching its surface is just swallowed by it. It appears black, as radiation is neither emitted nor reflected by it.

81) Why do water pipes burst in severe cold winters?
Ans: Water freezes in pipes during winters, when the temperature goes below 0 degree Celsius (i.e., freezing point of water). It expands and in the process exerts pressure on the water pipes, thereby sometimes bursting them.

82) Most aircrafts and ships have their front shape pointed. Why?
Ans: The shape of many objects, viz. aeroplanes, rockets, ships, etc. moving through air or water, are designed in such a way that friction can be reduced between the objects and air/water. Such type of body is known as streamlined and the process is known as streamlining.

83) An athlete runs some distance before taking jump, why?
Ans: An athlete runs a certain distance before actually jumping in order to increase his speed, and thereby, his inertia of motion. This increased inertia of motion enables him to jump a longer distance.

84) It is difficult to drown in the Dead Sea. Why?
Ans: The water of Dead Sea has a salt content of 27%. Therefore, its density is much greater than that of ordinary sea water and it also offers a greater upthrust. Hence, the body weighs less than an equal volume of Dead Sea water and is thus, able to float.

85) Why aquatic animals have soft skeleton unlike those of the terrestrial animals?
Ans: The density of animals and fish living in water is almost the same as the density of water. Therefore, their weight is almost completely balanced by buoyancy. That is why they do not need massive skeleton like those of terrestrial animals.

86) Why does a swimming pool appear less deep than it really is?
Ans: When rays of light start from the bottom of a pool and travel from water to air, they are refracted away from the normal because they travel from a denser medium to a rarer medium. As a result, a virtual image of bottom is formed above the bottom. Hence, a swimming pool appears less deep than it really is.

87) Why is electrical wiring in parallel better?
Ans: electrical wiring in parallel is better because all the lines will have the same potential difference and if one line gets fused the other lines remain unaffected.

88) It is easier to swim in sea water than in river water. Explain.
Ans: The density of sea water is more than that of the river water. Therefore, the weight of sea water displaced by the swimmer is more. Thus, buoyant force of upthrust on the swimmer increases, making it easier to swim in sea water.

89) A cold compress is applied on the forehead of a person suffering from high fever. Why?
Ans: Evaporation causes cooling. As the water evaporates, it absorbs heat from the forehead and helps in reducing the temperature.

90) A man with a load his head jumps from a high building. What will be the load experienced by him.
Ans: Zero, because the acceleration of his fall is equal to the acceleration due to gravity of the earth.

91) Why is spring made of steel and not copper?
Ans: The elasticity of steel is greater than that of copper.

92) Why is it easier to spray water to which soap is added?
Ans: Addition of soap decreases the surface tension of water. The energy for spray is directly proportional to surface tension.

93) A piece of chalk when immersed in water, emits bubbles. Why?
Ans: 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.

94) Why does a liquid remain hot or cold for a long time inside a thermo flask?
Ans: Because of the presence of air, which is poor conductor of heat, in between the double glass walls of a thermos flask.

95) Why is the boiling point of sea water more than that of pure water?
Ans: Sea water contains salts and other impurities with different points which jointly rise its boiling point.

96) Why is it recommended to add salt in water while boiling grams?
Ans: By addition of salt the boiling point of water gets which helps in cooking.

97) Why is soft iron used as an electromagnet?
Ans: Because it remains magnetic only till the current passes through the coil and loses its magnetism when the current is switched off (principle of electric bells)

98) Why does ink leak out of a partially filled pen when taken to a high altitude?
Ans: As we go up the pressure and the density of air go on decreasing. 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 air outside.

99) Why does some liquids burn while others do not?
Ans: A liquid burns if its molecules can combine with oxygen of the air with the production of heat. Hence, oil burns but water does not.

100) Oil and water do not mix. Why?
Ans: i) Molecules of oil are not bigger than that of water and therefore do not mix easily.
ii) Molecules of water are polar, i.e. they have opposite charges at two ends whereas oil molecules do not; as a consequence they tend to stay away from water molecule.
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