Question

For a first order reaction, nA$\rightarrow$B whose concentration vs time curve is as shown in the figure. If half life for the reaction is 24 minutes . Find out the value of n.

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

Answer: (C)

3

Answer 2

$nA \rightarrow B$

a

$a - x$ $\frac{x}{n}$ $t_{½}\text{ = 24 min}$

at t = 48 $\text{a-x = }\frac{x}{n}$

$a = \frac{(1 + n)x}{n};\frac{na}{1 + n} = x$

$\frac{\mathcal{l}n2}{24} = \frac{1}{48}\mathcal{l}n\frac{a}{a - \frac{na}{(1 + n)}}4 = \frac{a(1 + n)}{a}$ $\Rightarrow n = 3.$