RGU Question Paper Chemistry Semester IV 2021: Inorganic Organic and Physical Chemistry

JUNE – 2021

B. Sc. (IV Semester) Examination

CHEMISTRY

Paper: CHEM-241 (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 the following questions: 2x5 = 10

(a) Except $L{a}^{3+}, C{e}^{4+}, y{b}^{2+}$ and $L{u}^{3+}$, all Lanthanoids are paramagnetic. Why?

(b) The half life period of a first order reaction is 1 min 40 seconds. Calculate its rate constant.

(c) How many coulombs are required for the reduction of 1 mole of $C{r}_2{O}_7^{-2}$ to $C{r}^{3+}$?

(d) Explain why >C=O undergo nucleophilic addition reaction but >C=C<undergo electrophilic addition reaction?

(e) Write the IUPAC names of Lactic acid and Phthalic acid.

2. Answer any five questions: 4x5= 20

(a) What is Lanthanoids contraction? What are its consequences? 4

(b) Discuss the mechanism of decomposition of ozone using steady-state approximation. 4

(c) Calculate the emp of the following cell at 298k

4

(d) Write the mechanism of Aldol condensation. 4

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

(f) What are active methyl compounds? Starting from acetic acid, how will you prepare diethyl malonate. 1+3= 4

3. Answer any five questions: 5x6 = 30

(a) Discuss the ion-exchange method for the separation of Lanthanoids. 6

(b) (i) Derive kinetic equation for first order reaction. 3

(ii) The rate of reaction triples when the temperature changes from 200C to 500C. Calculate Ea (log3 = 0.4771). 3

(c) (i) What is liquid junction potential? How it can be eliminated? 2

(ii) For a particular cell E and 200C, 250C and 300C are 0.0663, 0.06839 and 0.07045 V respectively. Calculate ΔS and ΔH for the reaction at 250C. Given n=1 for the cell. 4

(d) Describe with mechanism the reactions of ammonia derivatives with carbonyl compound. 6

(e) (i) Maleic acid forms an anhydride on heating, but fumeric acid does not. Explain. 2

(ii) How will your convert Acetylene to Tantaric acid and Glycerol to Citric acid? 2+2= 4

(f) Write short notes on the following: 2x3= 6

(i) Claisen-Schmidt reaction

(ii) Michael addition

(iii) Dieckmann reaction