The t_0.5 for the first order reaction.

PCl₅(g) $\to$PCl₃(g) + Cl₂(g) is 20 min. The time in which the conc. of PCl₅ reduces to 25% of the initial conc. is close to 

1. 22 min

2. 40 min

3. 90 min

4. 50 min

For a certain reaction, 10% of the reactant dissociates in 1 hour, 20% of the reactant dissociate in 2 hour, 30% of the reactant dissociates in 3 hour. Then the units of the rate constant is:-

(1) hour^-1

(2) mol L^-1 hr^-1

(3) L mol L^-1 sec^-1

(4) mol L sec^-1

If the activation energy of a reaction is zero, how does the rate constant of the reaction change with temperature?

1. Increases with the increase in temperature

2. Decreases with the decrease in temperature

3. Decreases with the increase in temperature

4. Is nearly independent of temperature

 For the pseudo first order reaction A + B $\to$ P, when studied with 0.1 M of B is given by -d[A]/dt =k[A] where K = 1.85 x 10⁴ sec^-1. Calculate the value of rate constant for second order reaction :

(1) 1.85 x 10⁴

(2) 1.85 x 10^-4

(3) 1.85 x 10^-5

(4) 1.85 x 10⁵

When initial concentration of a reactant is doubled in a reaction, its half-life period is not affected. The order of the reaction is

(1) zero

(2) first

(3) second

(4) more than zero but less than first

In a zero order reaction for every 10° rise of temperature, the rate is doubled. If the temperature is increased from 10°C to 100°C, the rate of the reaction will become

(a) 256 times
(b) 512 times
(c) 64 times
(d) 128 times

Which one of the following statements for the order of a reaction is incorrect?

(1) Order is not influenced by stiochiometric coefficient of the reactants

(2) Order of reaction is sum of power to the concentration terms of reactants to express the rate of reaction

(3) Order of reaction is always whole number

(4) Order can be determined only experimentally

Half-life period of a first order reaction is 1386s. The specific rate constant of the reaction is

(a) 5.0 x 10^-3s^-1

(b) 0.5 x 10^-2s^-1

(c) 0.5 x 10^-3s^-1

(d) 5.0 x 10^-2s^-1

For the reaction, N₂ + 3H₂ $\to$2NH₃, if $\frac{\mathrm{d}\left[{\mathrm{NH}}_3\right]}{\mathrm{dt}}$= 2x10^-4 mol L^-1s^-1, the value of $-\frac{\mathrm{d}\left[{\mathrm{H}}_2\right]}{\mathrm{dt}}$ would be :

1. 3x10^-4 mol L^-1s^-1

2. 4x10^-4 mol L^-1s^-1

3. 6x10^-4 mol L^-1s^-1

4. 1x10^-4 mol L^-1s^-1

If 60 % of a first-order reaction is completed in 60 minutes, 50 % of the same reaction takes approximately:
(log4 = 0.60, log5 = 0.69)