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

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

2. –1

3. 1

4. –2

For a first-order reaction A → B the reaction rate at a reactant concentration of 0.01M is found to be $2.0\times {10}^{-5}\text{ mole }{\mathrm{L}}^{-1}{\mathrm{s}}^{-1}$. The half-life period of the reaction is:
1. 300s
2. 30s
3. 220s
4. 347s

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. $\frac{1}{32}$

The rate of a first-order reaction is 1.5 ×10^–2 mol L^–1 min^–1 at 0.5 M concentration of the reactant. The half-life of the reaction is:

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:

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