CHEMISTRY, PAPER-I CSS PAST PAPER 2010

CHEMISTRY, PAPER-I

FEDERAL PUBLIC SERVICE COMMISSION

COMPETITIVE EXAMINATION FOR

RECRUITMENT TO POSTS IN BPS-17 UNDER

THE FEDERAL GOVERNMENT, 2010

CHEMISTRY, PAPER-I

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(PART-I) 30 MINUTES MAXIMUM MARKS:20

TIME ALLOWED:

(PART-II) 2 HOURS & 30 MINUTES MAXIMUM MARKS:80

PART – I (MCQ)

(COMPULSORY)

Q.1. Select the best option/answer and fill in the appropriate box on the Answer Sheet. (20)

(i) When an electron is brought from infinite distance close to the nucleus of the atom, the energy of

Electron-nucleus system?

(a) increases to a smaller negative value (b) decreases to a greater negative value

(c) decreases to a smaller positive value (d) increases to a greater positive value

(ii) The probability of finding the electron in the nucleus is:

(a) 100% due to forces of attraction (b) finite for all orbitals

(c) Zero for all orbitals (d) Zero for some orbitals and finite for others

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 (iii) When Zn metal is kept in CuSO4 solution, copper is precipitated and ZnSO4 is formed because:

(a) Atomic number of Zinc is smaller than copper

(b) Atomic number of Zinc is larger than copper

(c) Standard reduction potential of Zinc is more than that of copper

(d) Standard reduction potential of Zinc is less than that of copper

(iv) Electrolytes when dissolved in water, dissociate into their constituent ions, the degree of

dissociation of an electrolyte increases with the:

(a) Presence of a substance yielding common ion

(b) Decreasing temperature

(c) Decreasing concentration of electrolyte

(d) Increasing concentration of electrolyte

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 (v) There is a large positive entropy change for an exothermic reaction. It means that the reaction

will be:

(a) possible at high temperatures only (b) impossible at all temperatures

(c) possible at low temperatures only (d) possible at all temperatures

(vi) Which of the following statement is false?

(a) the temperature of the system will fall if an exothermic reaction is isolated from its

surroundings

(b) Energy is absorbed when one compound is converted into another with higher heat content

(c) the temperature of the system is likely to fall if heat is absorbed during the course of a

reaction

(d) None of these

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 (vii) The H_____ bond is strongest in:

(a) S__H ……O (b) O_H …….S (c) F_H ……..O (d) F_H ……..S

(viii) Heavy water contains:

(a) Large amount of salts (b) Deuterium (c) O18 (d) O16

(ix) pH + pOH of a solution is:

(a) 7 (b) Zero (c) 14 (d) -14

(x) The compound that is not Lewis acid:

(a) BF3 (b) BaCl2 (c) SnCl4 (d) AlCl3

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 (xi) Strongest acid having Ka:

(a) 104 (b) 10-4 (c) 1 (d) 10-2

(xii) Ore of Aluminium:

(a) Calamine (b) Dolomite (c) Bauxite (d) Limestone

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NOTE: (i) First attempt PART-I (MCQ) on separate Answer Sheet which shall be taken back

after 30 minutes.

(ii) Overwriting/cutting of the options/answers will not be given credit.

(iii) Scientific calculator is allowed

Roll Number

CHEMISTRY, PAPER-I

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 (xiii) Oxidation number of S in sulphuric acid:

(a) Four (b) Six (c) Two (d) Eight

(xiv) d-block elements form coordination compounds because of:

(a) Small Cationic size (b) Large ionic Charge

(c) Unfilled d-orbitals (d) Filled d-orbitals

(xv) Brass is an alloy of:

(a) Cu and Zn (b) Cu, Ni, Zn (c) Cu and Ni (d) Cu, Al, Zn

(xvi) Urea is a high quality nitrogenous fertilizer with:

(a) 76% nitrogen (b) 46% nitrogen (c) 66% nitrogen (d) 26% nitrogen

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 (xvii) Diamond is:

(a) Good conductor of electricity (b) Bad conductor of electricity

(c) Bad conductor on heating (d) Good conductor on heating

(xviii) Carbon monoxide is poisonous gas because it:

(a) replaces oxygen from lungs (b) forms carboxy haemoglobin

(c) Forms carbon dioxide with oxygen (d) has a sweet smell

(xix) Rust is:

(a) FeO + Fe(OH)2 (b) Fe2O3 + Fe(OH)2 (c) Fe2O3 (d) Fe2O3 + Fe(OH)3

(xx) Calcium Carbide reacts with water to give:

(a) Methane (b) Ethylene (c) Acetylene (d) Ethane

PART – II

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NOTE:

(i) PART-II is to be attempted on the separate Answer Book.

(ii) Attempt ONLY FOUR questions from PART-II. All questions carry EQUAL marks.

(iii) Extra attempt of any question or any part of the attempted question will not be

considered.

Q.2. (a) Derive the Principal Quantum number from schrodinger wave equation and justify that if the

orbit of hydrogen atom is spherically symmetrical then expression for energy of electron is the

same as deduced by Bohr. (12)

(b) An atom of Helium is moving in one Dimensional box of width 10-2 m. Calculate the energy

difference between second and third energy level. (8)

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Q.3. (a) How do you measure the pH of a solution by potentiometric method using: (15)

(i) Hydrogen Electrode (ii) Glass Electrode

(b) Calculate the pH of a buffer solution containing 0.2M acetic acid and 0.02 M sodium acetate.

pKa of acetic acid is 4.73. (5)

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Q.4. (a) Define following types of processes: (8)

(i) Isothermal (ii) Adiabatic (iii) Isochoric (iv) Isobaric

(b) How the pressure, temperature and volume of a gas are related to each other in adiabatic

process: (8)

(c) 1 mole of an ideal gas at 25oc is allowed to expand reversibly at constant temperature from

15dm3 to 30dm3 calculate the work done by gas: (4)

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Q.5. (a) What is acid rain? How is it produced? Give in detail its chemistry. (8)

(b) Discuss the harmful effects of acid rain on environment and human health. (8)

(c) Enlist major sources for air pollution. (4)

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Q.6. (a) Describe the composition of Portland cement. (6)

(b) Which raw materials are used to manufacture glass on industrial scale? (6)

(c) What is fibre glass? Describe its uses. (4)

(d) Which compounds are added to impart different colours to glass? (4)

Q.7. (a) How is urea manufactured in Pakistan, explain with flow sheet diagram? (10)

(b) Name at least four nigtrogenous fertilizers. (4)

(c) 5.35 gm NH4Cl is heated with excess of quick lime. What is the weight of ammonia obtained?

If this ammonia is dissolved in 1 litre of water, Calculate the normality of this solution. (6)

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Q.8. (a) What are transition metals? Discuss their characteristic features. (12)

(b) Why AgCl is soluble in NH3? (4)

(c) What are alloy steels, give some examples? (4)

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