The rate equation for a reaction,

A $\to$ B

is r = k[ A]⁰. If the initial concentration of the reactant is a mol dm^-3 the half-life period of the reaction is

• $\frac{\mathrm{a}}{2\mathrm{k}}$

• $\frac{\mathrm{k}}{\mathrm{a}}$

• $\frac{\mathrm{a}}{\mathrm{k}}$

• $\frac{2\mathrm{a}}{\mathrm{k}}$

52.

For a reaction, A+ B $\to$ Product, the rate is given by,

r = k[A]^1/2[B]²

What is the order of the reaction?

• 0.5

• 2

• 2.5

• 1

If 50% of a radioactive substance dissociates in 15 min, then the time taken by substance to dissociate 99% will be

• 50 min

• 100 min

• 99 min

• 150 min

For a first order reaction A $\to$ B, the reaction rate at reactant concentration of 0.01 M is found to be 2.0 x 10^-5 mol L^-1s^-1. The half-life period of the reaction is

• 220 s

• 30 s

• 300 s

• 347 s

The increase in rate of reaction is four times when the concentration of reactant is increased two times.The order of reaction is:

• Zero.

• First.

• Second.

• Third.

The rate of reaction between two reactants A and B decreases by a factor of 4, if the concentration of reactant B is doubled. The order of this reaction with respect to reactant B is

• -1

• -2

• 1

• 2

The rate constant for a first order reaction is 60 s^-1 .The time required to reduce the concentration of the reactant to $\frac{1}{10}\mathrm{th}$ of its initial value is:

• $3.8\times {10}^{-2 \sec }$

• $1097\times {10}^{3 }\sec$

• $1.26\times {10}^{13 }\sec$

• $2.01\times {10}^{13}\sec$

The half-life of a first order reaction having rate constant k =1.7 x10^-5 s^-1 is :

• 12.1 h

• 9.7 h

• 11.3 h

• 1.8 h

Given that the temperature co-efficient for the saponification of ethyl acetate by NaOH is 1.75. The value of activation is:

• 9.207 Kcal mol^-1

• 10.207 Kcal mol^-1

• 4.0456 Kcal mol^-1

• 7.041 Kcal mol^-1

The rate constant of a reaction depends on

• the temperature of a reaction

• the time of a reaction

• the extent of reaction

• the initial conc. of the reactant