CSS 2018 Chemistry Combined Papers Past Paper

Paper details

Examination

CSS

Year

2018

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 2018.

1. Q2 · Ions in solution(a). Explain de Broglie’s hypothesis and derive its equation. How Davisson and (10) Germer proved the dual nature of electron? (b). Explain transport number. How it can be determined by Hittorf ’s method for Ag+ (10) ions in AgNO 3 solution?
2. Q3 · standard electrode potentials(a). Explain the working of quinhydrone electrode. (5) (b). Calculate the standard heat of formation of propane (C 3 H 8 ) if its heat of (5) combustion is –2220.2 kJ mol–1. The heats of formation of CO 2 (g) and H 2 O(l) are –393.5 and –285.8 kJ mol–1 respectively. (c). Describe the criteria of spontaneity of a chemical process. Explain in terms of (10) change in entropy, enthalpy and free energy with derivation of necessary equations.
3. Q4 · Catalysis(a). Discussthe factors which can affect the rate of a chemical reaction. (5) (b). Explain Arrhenius equation. Discuss Arrhenius concept of activation energy and (8) explain it by graphical representation. (c). Explain enzyme catalysis with examples. Also give some characteristics of this (7) catalysis.
4. Q5 · confidence limits(a). What are colloids? How are they classified? Describe how colloidal solution of (8) sulphur can be prepared? (b). What is meant by confidence limits? Seven replicate analysis for mercury in (7) natural gas condensate gave following results in ng/mL: 21.9 21.5 19.9 21.3 21.7 23.8 24.7 Calculate the 95% and 99% confidence limits for these measurements. (c). Explain R f value. Suppose that components of a mixture are separated by paper (5) chromatography using a non-polar solvent like hexane. Describe and explain how the polarity of a compound in the mixture will affect its R f value?
5. Q8 · Theories of coordination complexes(a). Explain crystal field theory. How it differs from valence bond theory? Also (10) explain crystal field splitting. How crystal field stabilization energy of a complex is calculated? (b). Write systemic names of following compounds. (5) K 4 [NiF 6 ], K 3 [Fe(CN) 6 ], [Co(NH 3 ) 4 Cl 2 ]Cl, K 2 [PtCl 6 ], K 2 [Cu(CN) 4 ] (c). Write the coordination number and oxidation state of the metal ion in each of the (5) above stated complexes. Roll Number
6. Q6 · Valence bond theory (VBT)(a). What is electrophoresis? Explain its working principle and describe its different (7) applications as a separation and characterization technique. (b). Explain the paramagnetic behavior of O 2 molecule on the basis of molecular (6) orbital theory. Explain why the existence of He 2 molecule is not possible on the basis of MOT? (c). Explain the molecular shape of [Ni(CN) 4 ]2 ̅ with the help of valence bond theory. (7) Also discuss its magnetic behaviour.
7. Q7 · oxidation states(a). Using VSEPR theory, identify the type of hybridization and draw the structure of (5) OF 2 . What are oxidation states of O and F? (b). A buffer of pH 9.26 is made by dissolving x moles of ammonium sulphate and (5) 0.1 mole of ammonia into 100 mL solution. If pK b of ammonia is 4.74, calculate the value of x. (c). Explain soft and hard acids and bases (SHAB) concept with examples. How is it (10) able to explain the stability of complexes and reaction rates?
8. Q2 · Hyperconjugation(a) Define Resonance and Resonance effect. (10) (b) Write Short note on followings. (5+5) (20) (i) Tautomerism (ii) Hyperconjugation.
9. Q4 · Mechanism of electrophilic substitution reactionExplain electrophilic substitution reaction mechanism with the help of: (i) Nitration (ii) Sulphonation. (20)
10. Q5 · S configuration and(a) Distinguish between: (4×3=12) (i) Configuration and conformation (ii) Enantiomer and Diastreomers (iii) R. Convention and S. Convention (b) Define specific rotation. How do you measure using polarimeter? (8) (20)
11. Q8 · PrincipleExplain the following: (4 marks each) (20) (a) Beers Lamberts Law. (b) Wood Wards Fieser Rule (c) Hooks Law (d) Basic principle of NMR? (e) Chemical Shift.
12. Q7 · Proteins(a) Explain Aldol condensation reaction with examples. (10) (b) What are proteins? (5) (c) Explain Bio synthesis of cholesterol. (5)

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