By which can activation energy be calculated?
1.  At a constant temperature
2.  At two different temperature
3.  For reversible reaction
4.  For volatile reaction

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. $\frac{1}{32}$

If the bombardment of α-particle on \(N_{7}^{14}\)  emits protons, then new atom will be:
1. \(O_{8}^{17}\)

2. \(O_{8}^{16}\)

3. \(C_{6}^{14}\)$\mathrm{}$

4. Ne

If the half-life of a substance is 77 days then it's decay constant (days^-1) will be:

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

1. $\frac{d\left[B{r}^{-}\right]}{dt}=-\frac{3}{5}\frac{d\left[B{r}_2\right]}{dt}$

2. $\frac{d\left[B{r}^{-}\right]}{dt}=\frac{3}{5}\frac{d\left[B{r}_2\right]}{dt}$

3. $\frac{d\left[B{r}^{-}\right]}{dt}=-\frac{5}{3}\frac{d\left[B{r}_2\right]}{dt}$

4. $\frac{d\left[B{r}^{-}\right]}{dt}=\frac{5}{3}\frac{d\left[B{r}_2\right]}{dt}$

If at a given instant, for the reaction 2N₂O₅ → 4NO₂ + O₂ rate and rate constant are 1.02 × 10^-4  and 3.4 × 10^-5 sec ^-1 respectively, then the concentration of ${\mathrm{N}}_2{\mathrm{O}}_5$ at that time will be: 

1. 1.732 mol L⁻¹

2. 3.0 mol L⁻¹

3. $1.02$ $\times$ ${10}^{-4}$ mol L⁻¹

4. $3.4$ $\times$ ${10}^5$ mol L⁻¹

When a biochemical reaction is carried out in a laboratory outside the human body in the absence of an enzyme, then the rate of reaction obtained is ${10}^{-6}$ times. The activation energy of a reaction in the presence of an enzyme is:

1. $\frac{6}{RT}$
2. P is required.
3. Different from $E_a$ obtained in the laboratory.
4. Data is insufficient.

The half-life period of $C^{14}$ is:
1.  500 years
2.  5000 years
3.  50 years
4.  5 × ${10}^4$ years