Chemical Kinetics · Question 13

An organic compound undergoes first order decomposition. The time taken for decomposition to ( 18 )th and ( 110 )th of its initial concentration are t1/8 and t1/10 respectively. What is the value of t1/8 t1/10 10? ( 2 = 0.3)

1. 30
2. 9
3. 3
4. 0.9

A → B (first reaction) C → D (second reaction) Consider the above two first-order reactions. The rate constant for first reaction at 500 K is double of the same at 300 K. At 500 K, 50% of the reaction becomes complete in 2 hours. The activation energy of the second reaction is half of that of first reaction. If the rate constant at 500 K of the second reaction becomes double of the rate constant of first reaction at the same temperature; then rate constant for the second reaction at 300 K is 10-1 hour-1 (nearest integer).

A D is an endothermic reaction occurring in three steps (elementary). (i) A B, Hi = +ve (ii) B C, Hii = -ve (iii) C D, Hiii = -ve Which of the following graphs between potential energy (y-axis) vs reaction coordinate (x-axis) correctly represents the reaction profile of A D?

1. [figure]
2. [figure]
3. [figure]
4. [figure]

At 27 in presence of a catalyst, activation energy of a reaction is lowered by 10 kJ mol-1. The logarithm of ratio of k (catalysed)k (uncatalysed) is.... (Consider that the frequency factor for both the reactions is same)

1. 1.741
2. 0.1741
3. 17.41
4. 3.482

The half-life of 65Zn is 245 days. After x days, 75\% of original activity remained. The value of x in days is . (Nearest integer) (Given: 3 = 0.4771 and 2 = 0.3010)

For the thermal decomposition of reactant AB(g), the following plot is constructed. [figure] The half-life of the reaction is 'x' min. x = min. (Nearest integer)

[figure] Given above is the concentration vs time plot for a dissociation reaction : A nB. Based on the data of the initial phase of the reaction (initial 10 min), the value of n is .

1. 2
2. 5
3. 4
4. 3

Observe the following reactions at T(K). I. A products. II. 5Br-(aq) + BrO3-(aq) + 6H+(aq) 3Br2(aq) + 3H2O(l) Both the reactions are started at 10.00 am. The rates of these reactions at 10.10 am are same. The value of - [Br-] t at 10.10 am is 2 10-4 mol L-1 min-1. The concentration of A at 10.10 am is 10-2 mol L-1. What is the first order rate constant (in min-1) of reaction I?

1. 4 10-3
2. 2 10-3
3. 10-3
4. 10-2

A product (First order reaction). Three sets of experiments were performed for a reaction under similar experimental conditions: Run 1 100 mL of 10 M solution of reactant A Run 2 200 mL of 10 M solution of reactant A Run 3 100 mL of 10 M solution of reactant A + 100 mL of H2O added. The correct variation of rate of reaction is

1. Run 1 = Run 2 = Run 3
2. Run 3 < Run 1 < Run 2
3. Run 1 < Run 2 < Run 3
4. Run 3 < Run 1 = Run 2

The temperature at which the rate constants of the given below two gaseous reactions become equal is K. (Nearest integer) X Y, k1 = 106 e -30000T P Q, k2 = 104 e -24000T Given : 10 = 2.303