HCS Optional Paper 2014: Chemistry Optional Paper Frontier IAS
Baljit Dhaka
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HCS Optional Paper 2014: Chemistry Optional Paper Frontier IAS

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HCS Mains Chemistry Optional Paper 2014

Time : 3 Hours                                                                                                                                       M.M. : 150
Note i) Attempt five questions. All questions carry equal marks. Questions number 1 is compulsory. Answer any two questions from Part I and two questions from Part II. The parts of the same questions must be answered together and must not be interposed between answers to the questions. 
ii) In case of any discrepancy in the English and Hindi versions. English version will be taken as final.

Q1. Write short note on any six of the following:                                                      (6X5=30)
a) Resonance and Resonance energy. 
b) Langmuir Isotheorem 
c) 'HNMR spectra 
d) SHE 
e) John Teller Effect 
t) Aldol condensation 
g) Organic Polymers 
h) Plank's Formulation

                                                                      Part - I

Q2. (a) The potential energy of electron in H atom is -1.70 ev. Find the excited state of the electron?  (5)

(b) Oxygen molecule is paramagnetic. Explain on the basis of Molecular Orbital Theory (MOT)   (5)

(c) Which compounds among the following will give green colour in its flame test  (5)
 i) Mgcl2 ii) BaCl2 iii) NaCl iv) CaCl2

(d) In a beaker, a copper rod is dipped rn HCL while in another beaker another copper rod is dipped in water, explain what will be the difference in the reactions occuring in these two beakers.   (5)

(e) Explain in brief Bragg's law.     (5)

(f) Explain transition contraction.  (5)

Q3. Write short note on   (2X5=10)                                             
i) Hess law 
ii) I.P of Ga and Al

(b) Explain the increase/decrease in entropy in the following reactions   (2X5=10)
i) Liquid converted into solid 
ii) Temperature of a solid increased from 0'Kto 115'K

c) Explain collision theory and transition state theory.   (10)

Q4. Write short notes on    (2X5=10)
i) Chemical potential and Gibb's-Duham equation. 
iI) d-Orbital splitting and geometry of co-ordinate complexes.

(b) Explain the following  (2X5=10)
i) LiF is sparingly soluble in water whereas LiI is soluble. 
ii) I P of Boron is less, still it does not form ionic compounds.

(c) Calculate the value of radius ratio for tetrahedral geometry in ionic compounds.    (10)

                                                             Part - II

Q5. a) Explain while writing a note on the following :                                              (3X5=15)
i) Reactive intermediates, their structures and stability. 
ii) Singlet and triplet states. 
iii) SN1 and SN2reaction mechanisms

(b) Explain reaction mechanisms of 
i) Reformatsky reaction 
ii) Reimer-Tiemann reaction                                                                                 (2X7.5=15)

Q6. Explain the followings with reasons 
a) Vinayl halide is an aliphatic compound but its reactivity is similar to aryl halides.   (2x7.5=15) 
b) -complex and -complexes

(b) Complete the following reactions                                                                     (5X3=15)

Q7. Draw the chemical structures of the followings 
a) Polystyrene and Terylene                                                                      (3X5=15)
b) Teflon and Rayon 
c) Nylon ard Polyvinyl Chloride

(b) Compare the followings                                                                         (3X5=15)
a) Kinetic and Thermodynamic control 
b) Vibrational and Rotational spectra 
c) n * and *transitions