RGU Question Paper Chemistry Semester II 2021: Inorganic, Organic and Physical Chemistry (New)

 JUNE – 2021

B. Sc. (II Semester) Examination

CHEMISTRY

Paper: CHEM-121 (New Course)

(Inorganic, Organic and Physical Chemistry)

Full Marks : 60

Pass Marks : 35%

Time : Two and Half Hours

Note: (i) Answer all the questions.

(ii) The figures in the margin indicate full marks for the questions.

1. Answer all questions: 2x5= 10

(a) State and explain Bent’s rule.

(b) Which of the following pair of alkyl halide undergo faster SN2 reaction.

(c) Explain why phenol is more acidic than alcohol.

(d) Calculate the Miller indices for the faces having intercepts: 

(a) 2a:ub:3c (b) a/2:b/4:∞

(e) Calculate pH of 0.0001 M H2SO4 solution.

2. Answer any five questions: 4x5= 20

(a) In Nacl ionic crystal based length is 2.36 Ǻ and the experimental dipole moment is 8.5 D. Calculate the percentage ionic character in Nacl.

(b) Explain the followings: 2x2= 4

(i) Sand Meyer’s reaction

(ii) Benzyne Mechanism

(c) Complete the following reactions: 1x4= 4

(d) What is average velocity? At what temperature will He atom has the same root mean square speed as H2 molecule at ${27}^{\circ }C$?

(e) Define homogeneous equilibrium. Derive an expression for Kc for the reaction

(f) How will you convert: 1x4 = 4

(i) N-propyl chloride to n-hexane

(ii) Chlorobenzene to ethyl benzene

(iii) Phenol to benzene

(iv) Propene to propanol-1

3. Answer any five questions: 6x5= 30

(a) Explain the followings: 2x3= 6

(i) BF3 has no dipole moment but NF3 has

(ii) Dipole moment of NH3 is greater than that of NF3.

(iii) SF6 has regular geometry but X3F6 has distorted geometry.

(b) Discuss mechanism of SN1 and SN2 reactions. 2x3= 6

(c) Give the mechanism of followings: 2x3= 6

(i) Pinacol – Pinacolone rearrangement

(ii) Reimer – Tiemann Reaction

(d) Derive Bragg’s equation. Determine the interplanar spacing between the (221) plane of a cubic lattice of length 4.5 Ȧ. 4+2= 6

(e) (a) When N2 and H2 are mixed in the proportion 1:3 at 50atm and 6500c, the equilibrium concentration of ammonia is 25% by weight. Calculate the equilibrium constant kp. 3

(b) Derive Henderson eqn for acidic buffer solution. 3

(f) (i) Calculate the average energy of the molecule of C2H6 at 300K using law of equipartition of energy. 3

(ii) What do you mean by salt hydrolysis? Derive expression for pH of a salt of strong acid and a weak base. 1+2= 3