What does Z_AB represent in the collision theory of chemical reactions?

1.	The fraction of molecules with energies greater than Ea
2.	The collision frequency of reactants, A and B
3.	Steric factor
4.	The fraction of molecules with energies equal to Ea

The unit of rate constant for a zero-order reaction is:

1. ${\mathrm{s}}^{-1}$

2. $\mathrm{mol}$ ${\mathrm{L}}^{-1}{\mathrm{s}}^{-1}$

3. $\mathrm{L}$ ${\mathrm{mol}}^{-1}{\mathrm{s}}^{-1}$

4. ${\mathrm{L}}^2{\mathrm{mol}}^{-2}{\mathrm{s}}^{-1}$

The half-life of a certain enzyme catalysed reaction is 138 s, that follow the 1st order kinetics. The time required for the concentration of the substance to fall from 1.28 mg L^–1 to 0.04 mg L^–1, is:

1. 276 s 

2. 414 s

3. 552 s 

4. 690 s

The rate of the reaction $2{\mathrm{N}}_2{\mathrm{O}}_5\to 4{\mathrm{NO}}_2+{\mathrm{O}}_2$  can be written in three ways:

$\frac{-d\left[N_2{O}_5\right]}{dt}=k\left[N_2{O}_5\right]$
$\frac{d\left[N{O}_2\right]}{dt}=k\text{'}\left[N_2{O}_5\right]$
$\frac{d\left[O_2\right]}{dt}=k\text{'}\text{'}\left[N_2{O}_5\right]$

The relationship between k and k′ and between
k and k′′ are-

1. k′ = k, k′′= k 

2. k′= 2k; k′′= k

3. k′= 2k, k′′= k/2 

4. k′ = 2k; k′′= 2k

The rate of the reaction

2NO + Cl₂ → 2NOCl is given by the rate equation
rate = k[NO]²[Cl₂]

The value of the rate constant can be increased by: 

1. Increasing the concentration of NO
2. Increasing the concentration of Cl₂
3. Increasing the temperature
4. All of the above

Activation energy $E_a$ and rate constant (k₁ and k₂) of a chemical reaction at two different temperatures (T₁ and T₂) are related by:

The half-life for a zero-order reaction having 0.02 M initial concentration of reactant is 100 s. The rate constant (in mol L^–1 s^–1) for the reaction is:

1. $1.0\times {10}^{-4}$

2. $2.0\times {10}^{-4}$

3. $2.0\times {10}^{-3}$

4. $1.0\times {10}^{-2}$

A 300-gram radioactive sample has a half-life of 3 hours. After 18 hours the remaining quantity will be:

1. 4.68 gram

2. 2.34 gram

3. 3.34 gram

4. 9.37 gram

If the concentration of a solution is changed from 0.2 to 0.4, then what will be rate and rate constant. The reaction is of first order and rate constant is $K=1\times {10}^{-6}$: 

1. $2\times {10}^{-7}$ $;$ $1\times {10}^{-6}$

2. $1\times {10}^{-7}$ $;$ $1\times {10}^6$

3. $4\times {10}^{-7}$ $;$ $1\times {10}^{-6}$

4. $2\times {10}^{-3}$ $;$ $1\times {10}^{-3}$

Half-life of a radioactive sample is 4 days. After 16 days what quantity of matter remains undecayed?

1. $\frac{1}{4}$

2. $\frac{1}{8}$

3. $\frac{1}{16}$

4. $\frac{1}{32}$