Consider the following statements :
I. Increase in concentration of reactant increases the rate of a zero order reaction
II. Rate constant k is equal to collision frequency A , if E_a =0

III. Rate constant k is equal to collision
frequency A , if E_a = ∞
IV. ln k vs T is a straight line
V. ln k vs 1/T is a straight line

Correct statements are :

• I and IV

• II and V

• III and IV

• II and III

642.

The chemical reaction, 2O₃ $\to$ 3O₂ proceeds as follows:

Step 1 : O₃ $\rightleftharpoons$ O₂ + O  ...(fast)

Step 2 : O + O₃ $\to$2O₂ ...(slow)

The rate law expression should be

• r = k' [O₃][O₂]

• r = k'[O₃]²[O₂]^-1

• r = k'[O₃]²

• unpredictable

A first order reaction, which is 30% complete in 30 minutes has a half-life period of

• 102.2 min

• 58.2 min

• 24.2 min

• 120.2 min

The role of a catalyst is to change :

• enthalpy of reaction

• equilibrium constant

• activation energy of reaction

• Gibbs energy of reaction

Which one of the following options is not correct for the decomposition reaction of NH₃ ?

2NH₃ (g) $\underset{\mathrm{Pt} \mathrm{catalyst}}{\overset{1130 \mathrm{K} , \mathrm{at} \mathrm{high} \mathrm{p}}{\to }}$ N₂ (g) + 3H₂ (g)

• Rate of reaction = rate constant

• Further increase in pressure will change the rate of reaction

• Rate of decomposition of NH₃ will remain constant until NH₃ disappears completely

• Rate of reaction depends on concentration of NH₃

For the reaction , aA + bB $\to$ cC , if -3$\frac{\mathrm{d}\left[\mathrm{A}\right]}{\mathrm{dT}}$ = -3$\frac{\mathrm{d}\left[\mathrm{B}\right]}{\mathrm{dt}}$ = +1.5$\frac{\mathrm{d}\left[\mathrm{C}\right]}{\mathrm{dt}}$ then a , b , c respectively are :

• 1 , 3 , 2

• 1 , 2 , 3

• 3 , 2 , 1

• 3 , 1 , 2

For reaction aA $\to$ xP, when [A] = 2.2 mM, the rate was found to be 2.4 mM s^-1. On reducing concentration of A to half, the rate changes to 0.6 mM s^-1.The order of reaction with respect to A is

• 1.5

• 2.0

• 2.5

• 3.0

75% of a zero order reaction complete in 4 h 87.5% of the same reaction completes in

• 6h

• 12h

• 8h

• 2h

For the reaction A_(g)$\to$B_{( g)}+ C_(g), the rate constant is given as (P_i is initial pressure and P_t is pressure at time t)

• $k=\frac{2.303}{\mathrm{t}}\log \frac{{\mathrm{P}}_{\mathrm{i}}}{{\mathrm{P}}_{\mathrm{t}}}$

• $k=\frac{2.303}{\mathrm{t}}\log \frac{{\mathrm{P}}_{\mathrm{i}}}{(2{\mathrm{P}}_{\mathrm{i}}-{\mathrm{P}}_{\mathrm{t}})}$

• $k=\frac{2.303}{\mathrm{t}}\log \frac{2{\mathrm{P}}_{\mathrm{i}}-{\mathrm{P}}_{\mathrm{t}}}{{\mathrm{P}}_{\mathrm{i}}}$

• $k=\frac{2.303}{\mathrm{t}}\log \frac{{\mathrm{P}}_{\mathrm{i} }-{\mathrm{P}}_{\mathrm{t}}}{2{\mathrm{P}}_{\mathrm{i}}}$

The activation energy for most of the reactions is approximately 50 kJ mol^-1 .The value of temperature coefficient for such reactions is :

• > 2

• > 3

• < 1

• > 4