Question

${}_2^{M}A\left(g\right){\to }_{Z-4}^{M-8}B\left(g\right)+\alpha -particles$
The radioactive disintegration follows first order kinetics. Starting with 1 mol of in a 1 litre closed flask at ${27}^{\circ }$C, pressure set up after two half-lives is approximately

• A. 25 atm
• B. 12 atm
• C. 37 atm
• D. 40 atm

Answer 1

The correct option is C 37 atm

$InitialP=\frac{1\times 0.0821\times 300}{1}=24.63{}^{}{}_2^{M}A\left(g\right){\to }_{Z-4}^{M-8}B\left(g\right)+\alpha -particles1001-0.750.752\times 0.75=1.5$
= 0.25
Total no.of moles = 0.25 + 0.75 + 1.5 = 2.5
$\frac{P_f}{P_i}=\frac{2.5}{1}{P}_f=2.5\times 24.63$
Pressure increased = 61.57-24.63
= 37 atm