Chemistry CSS Past Paper 2012

CSS Chemistry Past Papers 2012 can help you to prepare your CSS Exams 2013 or any other CSS exams.

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 ———– C6H12O6 + 6O2

(ii) State and explain the relationship of Ionization Energy of an atom with its reactivity. (8)

(iii) Explain : Why dipole movement of BF3 is Zero? (2)

(iv) Why diploe movement of NH3 is greater than that NF3? (2)

(v) Why does SO2 have dipole movement while CO2 does not?(4)

Q . No. 3

(i) Differentiate between a gague and slag. Give an example of a metallurgical step where slag, flux and gangue are involved simultaneously. (6)

(ii) Describe the different industrial process for preventing the metals from corrosion. (8)
(iii) Draw diagram extraction of aluminium from soil. (4)
(iv) Name the flux used in the extraction of Iron. (2)

Q No. 4

(i) Given the reaction: XeF4 + F ———- XeF6
Predict the change in hybridization and consequent, final shape of the molecule followed in the above reaction. (4)

(ii) Valence shell electron pair replusion theory can be used to predict the shapes of molecules, Using this theory explain the shapes acquired by BF3 and CH4. (8)

(iii) Explain why HOH bond angle in H2O is slightly less than the tetrahedral angle of 109.5. (8)

Q No. 5

(i) A galvanic cell consists of mettalic Zn plate immersed in 0.1 M Zn (NO3)2 solution and mettalic plate of lead in .02 M Pb (NO3)2 solution. Given
E Zn2 + Zn= -0.76 V,
Pb2 + Pb = -0.13V
Write the half-cell reaction. (3,3,6,6,2)

(ii) Write the overall reaction of the cell.
(iii) Calculate the e.m.f of the cell.
(iv) Explain the Nernest 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. (3,3,3,3,6,2)
(i) Bleaching Powder
(ii) Casutic 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 realted to spontaneity of a system and to a system in equilibrium. (4)
(ii) Entropy change liquid water to steam at 373 K is 109 J mol-1K-1. What is the enthalpy change for the transition of liquid water to steam at 373 K. (4)

(iii) Define Gibbs free energy function. Explain its significance. (4)
(iv) Explain following (8)
(a) Ion selective electrode
(b) Quantum Yield
(c) Fuel Cell
(d) Lanmuir Isotherm

Q No. 8

(i) Why is chlorination not the most desirable method of disinfecting polluted water? (3)
(ii) What are anthropogenic pollutants? Give two examples each of primary and secondary pollutants. (4)

(iii) What are the effects of detergents on the fresh water bodies? (3)
(iv) Calculate the pH of 0.001 M HCl solution. (2)
(iv) How gloable warming is caused? List and explain four consequences of green house effect.(8)

Paper II

Q No.2.

a. What is the difference between Valence Bond Theory and Molecular Orbital Theory? (8)
b. Draw the Molecular orbital Diagram of CO molecule showing sigma, pi bonding, non-bonding and anti bonding molecular orbital. (8)
c. Discuss the difference between the Hybridization of SO2 and SO3. (4)

Q No.3.

a. Discuss the rate law of SN1 mechanism. (6)
b. What is the importance of half life in the determination of order of reaction? (6)
c. What is the pseudo first order reaction? What is its importance? (8)

Q. No. 4

a. Describe the difference between physical adsorption and chemiadsorption. (8)
b. The data of Langmuir for the adsorption of Nitrogen and 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 12.3 13.4 15.1 17.9 19.0 21.6 23.9 25.5 28.2 30.8
cumm at 20K
& 760MM
Estimate the surface area of the mica sample in the Langnuir experiment? (8)

c. Define Homogeneous catalyst & Heterogeneous catalyst. (4)

Q. No. 5

a. Discuss stereo isomerism in compounds having 2 similar asymmetric carbon atoms. (6)

b. Draw Fischer projection formulae of the following compounds. (8)

i) R & S 2 – Bromopentane
ii) R & S 3 – chloro-1-pentane.
iii) R & S 3-chloro-3-methylocatne
iv) R & S 2-pentanol

c. What do you understand by the terms Z & E isomers? Illustrate your answer with example. (6)

Q. No. 6

a. Discuss the structure of Grignard Reagent. (4)

b. How these compounds can be prepared by Grignard Reagent? (12)

i) Ethane ii) Acetic Acid iii) 2-Butanol

c. What is the diazotization reaction? (4)

Q. No. 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. No. 8

a. Write main steps in the formation of following polymers: (3+3)

i) Nylon 6,6 and polyester by condensation polymerization

ii) Polyethlene by Free Radical polymerization

b. Differentiate between oil, fat & wax with examples. (9)
c. What are alkaloids? (5)