Federal Public Service Commission (FPSC)
Competitive Examination for Recruitment to BPS-17 Posts under the Federal Government
Time Allowed: 3 Hours
MAXIMUM MARKS: 100 Marks
CHEMISTRY, PAPER-I
Attempt FIVE questions in all, Including Questions No.1 which is COMPULSORY, All questions carry EQUAL marks.
Q.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 1.08g of glucose?
6CO₂(g) + 6H₂O(l) C₆H₁₂O₆(s) + 6O₂(g) (04)
(ii) State and explain the relationship of ionization energy of an atom with its reactivity. (08)
(iii) Explain: Why dipole movement of BF₃ is Zero? (02)
(iv) Why dipole movement of NH₃ is greater than that NF₃? (02)
(v) Why does SO₂ have dipole movement while CO₂ does not? (04)
Q.3. (i) Differentiate between a gangue and slag. Give an example of a metallurgical step where slag, flux and gangue are involved simultaneously. (06)
(ii) Describe the different industrial process for preventing the metals from corrosion. (08)
(iii) Draw diagram extraction of aluminum from soil. (04)
(iv) Name the flux used in the extraction of Iron. (02)
Q.4. (i) Given the reaction: XeF₄(g) + F⁻(g) XeF₅⁻(g) [or XeF₄(g) + F₂(g) XeF₆(g)]
Predict the change in hybridization and consequent, final shape of the molecule followed in the above reaction. (04)
(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. (08)
(iii) Explain why HOH bond angle in H₂O is slightly less than the tetrahedral angle 109.5°. (08)
Q.5. (i) A galvanic cell consists of metallic Zn plate immersed in 0.1 M Zn(NO₃)₂ solution and metallic plate of lead in 0.02 M Pb(NO₃)₂ solution. Given E°(Zn²⁺/Zn) = -0.76 V, E°(Pb²⁺/Pb) = -0.13 V. Write the half-cell reactions.
(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. (3,3,6,6,2)
Q.6. Write one reaction each for the preparation of the following. Also write one use of each product.
(i) Bleaching powder (ii) Caustic Soda (iii) Quick lime (iv) Ammonia (3,3,3,3)
(v) How is caustic soda manufactured by Using Nelson’s cell? (6)
(vi) What is an ideal solution? (02)
Q.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. (06)
(ii) Entropy change from liquid water to steam at 373 K is 109 J mol⁻¹ K⁻¹. What is the enthalpy change for the transition of liquid water to steam at 373 K. (04)
(iii) Define Gibbs free energy function. Explain its significance. (06)
(iv) Explain following: (a) Ion selective electrode (b) Quantum yield (c) Fuel Cell (d) Langmuir isotherm (04)
Q.8. (i) Why is chlorination not the most desirable method of disinfecting polluted water? (04)
(ii) What are anthropogenic pollutants? Give two examples each of primary and secondary pollutants. (04)
(iii) What are the effects of detergents on fresh water bodies? (04)
(iv) Calculate the pH of 0.001M HCl solution. (04)
(v) How global Warming is caused? List and explain four consequences of green house effect. (04)
CHEMISTRY, PAPER-II
Attempt FIVE questions in all, Including Questions No.1 which is COMPULSORY, All questions carry EQUAL marks.
Q.2. (a) What is the difference between Valence Bond Theory and Molecular Orbital Theory? (08)
(b) Draw the molecular orbital diagram of CO molecule showing sigma pi bonding, nonbonding and anti bonding molecular orbitals. (08)
(c) Discuss the difference between the hybridization of SO₂ and SO₃. (04)
Q.3. (a) Discuss the rate law of S_N1 mechanism. (06)
(b) What is the importance of half life in the determination of order of reactions? (06)
(c) What is pseudo first order reaction? & What is its importance? (08)
Q.4. (a) Describe the differences between physical adsorption and chemiadsorption. (08)
(b) The data of Langmuir for the adsorption of Nitrogen on mica at 90 K given:
P(atm): 2.8, 3.4, 4.0, 4.9, 6.0, 7.3, 9.4, 12.8, 17.9, 23.5
Amt adsorbed x (mm³ at 20°C & 760mm): 12.0, 13.4, 15.1, 17.9, 19.0, 21.6, 23.9, 25.5, 28.2, 30.8
Estimate the surface area of the mica sample in the Langmuir experiment? (08)
(c) Define Homogeneous catalyst & Heterogeneous catalyst. (04)
Q.5. (a) Discuss stereoisomerism in compounds having 2 similar asymmetric carbon atoms. (06)
(b) Draw Fischer projection formulae for the following compounds.
i. R & S 2-Bromopentane ii. R & S 3-chloro-1-pentane
iii. R & S 3-chloro-3-Methyloctane iv. R & S 2-pentanol (08)
(c) What do you understand by the terms Z & E isomers? Illustrate your answer with example. (06)
Q.6. (a) Discuss the structure of Grignard reagent. (04)
(b) How these compounds can be prepared by Grignard reagent? (i) Ethane (ii) Acetic acid (iii) 2-Butanol (12)
(c) What is diazotisation reaction? (04)
Q.7. How would you prepare the following compounds from benzene? Name each reaction as well. (20)
(i) Acetophenone (ii) Bromobenzene (iii) Maleic anhydride (iv) Toluene (v) Benzaldehyde
Q.8. (a) Write main steps in the formation of following polymers:
i. Nylon 6,6 and polyester by condensation polymerization.
ii. Polyethylene by Free Radical Polymerization. (06)
(b) Differentiate between oil, fat & wax with examples. (07)
(c) What are alkaloids? (07)
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