First Order Reaction

Q. What is the half life period of a radioactive substance if 87.5$\%$ of any given amount of the substance disintegrates in 40 minutes?

1. 160 min
2. 10 min
3. 20 min
4. 13.58 min

Q.

What is the effect of temperature on the rate constant?

Q. The rate of a first order reaction $R\to P$is $7.5\times {10}^{-4}mol{L}^{-1}{s}^{-1}$ when the concentration of R is 0.5 mol $L^{-1}$.

The rate constant is

1. $1.5\times {10}^{-5}{s}^{-1}$
2. $2.5\times {10}^{-5}{s}^{-1}$
3. $1.5\times {10}^{-3}{s}^{-1}$
4. $4.16\times {10}^{-7}{s}^{-1}$

Q. The rate for a first order reaction is $0.639\times {10}^{-2}mold{m}^{-1}mi{n}^{-1}$ and the initial concentration is 0.2 mol $d{m}^{-3}$. The half-life period is

1. 1200 s
2. 0.33 s
3. 20 s
4. 600 s

Q. For the reaction :
$2N_2{O}_5\to 4N{O}_2+O_2$
Rate and rate constant $1.02\times {10}^{-4}$ and $3.4\times {10}^{-5}{s}^{-1}$ respectively, then concentration of $N_2{O}_5$ at that time will be

1. $1.732$
2. $3$
3. $1.02\times {10}^{-4}$
4. $3.4\times {10}^5$

Q.

The rate law for the reaction:
$RCl+NaOH\to ROH+NaCl$ is given by;
Rate = $k\left[RCl\right]$. The rate of this reaction is

(IIT-JEE, 1990)

1. Doubled by doubling the concentration of NaOH

2. Halved by reducing the concentration of RCl by one half

3. Increases by increasing the temperature of the reaction.

4. Unaffected by change of temperature

Q. Graph between concentration of the product ‘x’ and time ‘t’ for A $\to$B is given below:

The graph between $-\frac{d\left[A\right]}{dt}$ and time will be of the type:

1. 
2. 
3. 
4.