**LEVEL – I **

1. A first order reaction is 87.5% complete in an hour. The rate constant of the reaction is

(A) 0.0346 min^{–1}

(B) 0.0693 h^{–1}

(C) 0.0693 min^{–1}

(D) 0.0346 h^{–1}

2. The half – life a first order reaction is 24 hours. If we start with 10M initial concentration of the reactant then conc. after 96 hours will be

(A) 6.25 M

(B) 1.25 M

(C) 0.125 M

(D) 0.625M

3. During the particular reaction 10% of the reactant decompose in one hour 20% in two hours 30% in three hours and so on. The unit of the rate constant is

(A) Hour^{–1}

(B) L mol^{–1} hour^{–1}

(C) mol L^{–1} hour^{–1}

(D) mol hour^{–1}

4. The temperature coefficient of a reaction is 2 , by what factor the rate of reaction increases when temperature is increased from 30°C to 80°C.

(A) 16

(B) 32

(C) 64

(D) 128

5. The rate constant, the activation and Arrhenius parameter of a chemical reaction at 25°C are 3 × 10^{–4} s^{–1} , 104.4 kJ mol^{–1} and 6 × 10^{14} s^{–1} respectively. The value of the rate constant at T −> ∞ is

(A) 2 × 10^{18}s^{–1}

(B) 6 × 10^{14}

(C) α

(D) 3.6 × 10^{30}s^{–1}

6. At 250°C, the half life for the decomposition of N_{2}O_{5} is 5.7 hour and is independent of initial pressure of N_{2}O_{5}. The specific rate constant is

(A) 0.693 / 5.7

(B) 0.693 × 5.7

(C) 5.7 / 0.693

(D) None

7. For a given reaction of first order, it takes 20 min , for the concentration to drop from 1 M L^{–1} to 0.6 ML^{–1} . The time required for the concentration to drop from 0.6 ML^{–1} to 0.36 ML^{–1} will be

(A) > 20 min

(B) < 20 min

(C) = 20 min

(D) ∞

8. In a first order reaction the a /(a – x) was found to be 8 after 10 min. The rate constant is

(A)( 2.303 × 3log2 )/10

(B) ( 2.303 × 2log3 )/10

(C) 10 × 2.303 × 2 log 3

(D) 10 × 2.303 × 3 log 2

9. For the reaction A + B −> Products, it si found that the order of A is 2 and of B is 3 in the rate expression. When concentration of both is doubled the rate will increase by

(A) 10

(B) 6

(C) 32

(D) 16

10. The rate law of the reaction A + 2B −> Product is given by d[Product]/dt = K[A]^{2}.[B]. If A is taken in large excess, the order of the reaction will be

(A) 0

(B) 1

(C) 2

(D) 3

__ANSWER:__

**1. A 2. D 3. C 4. B 5. B 6. A 7. C 8. A 9. C 10.B **