CSS 2019 Chemistry Combined Papers Past Paper

Paper details

Examination

CSS

Year

2019

Subject

Chemistry

Paper

Combined Papers

Subject type

Optional

Mode

Subjective

Questions recorded from this paper

These 12 question wordings are transcribed from CSS Vista’s structured Chemistry past-paper record for CSS 2019.

1. Q2 · Bohr’s atomic model(a) Describe the assumption of Bohr’s atomic model. Based on Bohr’s calculation, (8) establish the energy expression of the rotation of electrons in Hydrogen like atomic species. (b) Derive de-Broglie’s equation for the dual nature of matter. Apply this equation (6) for microscopic and macroscopic properties of substances. (c) What are the postulates of Quantum Mechanics? (6) (20)
2. Q8 · mobility of ions and transport number(a) Explain Kohlrausch’s Law? Give its applications. (7) (b) What is meant by transport number of ions? Give different methods for (7) determination of transport number. (c) What is specific conductance? How it can be determined by using Wheatstone (6) (20) bridge?
3. Q3 · Thermodynamics(a) What is Third law of thermodynamics? How it is used to determine the (7) entropies of substance. (b) Discuss the isothermal expansion of a gas and derive the equation for the work (7) done due to expansion of a gas. (c) Explain the law of corresponding states. (6) (20)
4. Q4 · transition state theory(a) Deduce the rate expression for 2nd order reaction where both the concentration (10) terms are same. What is the half-life period for the 2nd order reaction? (b) What is activation energy? How it can be determined? (5) (c) Write a note on Transition state theory of reaction rates. (5) (20)
5. Q5 · Catalysis(a) Develop a relation among phase, component and degree of Freedom. Draw a (10) complete diagram for water system. (b) What is catalysis? Differentiate between positive and negative catalysis. (6) (c) What is stoichiometry? Explain it with help of examples. (4) (20)
6. Q6 · Acids and Bases(a) State and explain Lowry-Bronsted theory and Lewis theory of acids and bases. (8) In what way Lewis theory differs from Bronsted theory. (b) Explain with the help of examples why pH of a buffer solution does not change (6) significantly on small addition of acids and bases. (c) What are indicators? How a suitable indicator can be chosen? Discuss. (6) (20)
7. Q7 · isomerism(a) Give an account of phenomena of isomerism in co-ordination compound with (8) suitable example. (b) Describe the extraction of thorium from mozite sand. (6) (c) Compare the properties of lanthanides and actinides? (6) (20)
8. Q4 · Chemistry of Aromatic Compounds(a) Describe the necessary conditions and reagents required to convert (8) benzene into the following. Nitrobenzene, Ethyl benzene, cyclohexane, Benz-aldehyde, Benzoic acid, and Chlorobenzene. (b) Draw all possible structures of aromatic compounds with the formula C 9 H 12 (6) containing the benzene ring. (c) How do you account for the fact that phenol is more easily attacked (6) (20) by electrophiles than nitrobenzene?
9. Q3 · Chemistry of Functional Groups(a) Prepare a plausible synthesis for each of the following transformation: (12) A. B. C. D. HO Br E. Br Br Br F. (b) Explain the type of hybridization in 1,3-Butadiene. (4) (c) Mention any three methods for preparation of Alkynes. (4) (20)
10. Q6 · Chemistry of Functional Groups(a) Describe two methods for preparation of salicylic acid? How would (10) you convert it into (a) Phenol, (b) Salol, (c) Benzoic acid and (d) Aspirin? Give its at least two medicinal uses. (b) How will you obtain the following from suitable mono carboxylic acid? (6) (a) Iso-butane (b) Butanone (c) Benzamide (d) Propionaldehyde. (c) Describe the mechanism of esterification of an acid. (4) (20)
11. Q5 · and amines with focus on reaction mechanism and applications(a) Outline stepwise reaction mechanism for the following reactions: (8) (i) SN1 reaction between bromoethane and NaOH. (ii) SN2 reaction between 2-chloro-2-methyl propane and NaCN. (b) Discuss the various factors, nature of substrate, solvent, catalyst, and the leaving (8) group in SN2 reaction. (c) How does methyl iodide react with the following reagents? (4) (20) Acetic acid, Mg, Alcoholic KOH and Na.
12. Q2 · Stereochemistry(a) Elaborate the optical isomerism with appropriate examples. (10) (b) Express the resolution and its applications. (5) (c) Explain the geometric isomerism in cyclic compounds. (5) (20)

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