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Arrow Chemistry papers 2012

Chemistry Paper I

Q No.2.
(i) Glucose is formed according to the following reaction, absorbing 2840 kJ of heat. How much energy will be given out by combustion of 1.08 of glucose? (4)
6CO2(g)+ 6H2O(l)C6H12O6(s) + 6O2 (g)
(ii) State and explain the relationship of ionization energy of an atom with its reactivity.
(iii) Explain: Why dipole movement of BF3 is Zero?
(iv) Why dipole movement of NH3is greater than that of NF3?
(v) Why does SO2 have dipole movement while CO2 does not?

Q No.3.
(i) Differentiate between a gangue and slag. Give an example of a metallurgical step where slag, flux, and gangue are involved simultaneously.
(ii) Describe the different industrial process for preventing the metals from corrosion.
(iii) Draw diagram extraction of aluminum from soil.
(iv) Name the flux used in the extraction of Iron.

Q No.4.
(i) Given the reaction: XeF4(g) + F(g)XeF6(g) (04) Predict the change in hybridization and consequent, final shape of the molecule followed in the above reaction.
(ii) Valence shell electron pair repulsion theory can be used to predict the shapes of molecules. Using this theory explain the shapes acquired by BF3 and CH4.
(iii) Explain why HOH bond angle in H2O is slightly less than the tetrahedral angle 109.5?

Q No.5.
(i) A galvanic cell consists of metallic Zn place immersed in 0.1 M Zn (NO3)2 solution and metallic plate of lead in 0.02 M Pb (NO3)2 solution. Given EoZn2 + Zn = -0.76 V, EoPB2 + Pb = -0.13 V Write the half cell reaction.
(ii) Write the overall reaction of the cell.
(iii) Calculate the e.m.f. of the cell.
(iv) Explain the Nernst heat theorem.
(v) Define enthalpy of formation.

Q No.6. Write one reaction each for the preparation of the following, Also write one use of each product.
(i) Bleaching Power
(ii) Caustic Soda
(iii) Quick Lime
(iv) Ammonia
(v) How is caustic soda manufactured by using Nelson's cell?
(vi) What is an ideal solution?

Q No.7.
(i) What do you understand by entropy? In what way the total entropy change is related to spontaneity of a system and to a system in equilibrium.
(ii) Entropy change from liquid water to steam at 373 K is 109J mol−1 K-1. What the enthalpy change for the transition of liquid water to steam at 373 K?
(iii) Define Gibbs free energy function. Explain its significance.
(iv) Explain following:
(a) Ion selective electrode
(b) Quantum yield
(c) Fuel Cell
(d) Langmuir isotherm

Q No.8.
(i) Why is chlorination not the most desirable method of disinfecting polluted water?
(ii) What are anthropogenic pollutants? Give two examples each of primary and secondary pollutants.
(iii) What are the effects of detergents on fresh water bodies?
(iv) Calculate the pH of 0.001 M HCl solution.
(v) How Global Warming is caused? List and explain four consequences of green house effect.
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