A balloon has a volume 400 ml at 0 ° C . The balloon is distended...

(i) Maximum stretching capacity $= 400 \times \dfrac{5}{4} = 500$ ml
$\dfrac{{V}_{1}}{{T}_{1}} = \dfrac{{V}_{2}}{{T}_{2}}$
or $\dfrac{400}{273} = \dfrac{{V}_{2}}{313}$
${V}_{2} = 458.61$ ml
If the volume becomes more than 500 ml it will burst. The volume is below 500 ml, hence it will not burst at 40 $° C$ .
(ii) $\dfrac{{V}_{1}}{{T}_{1}} = \dfrac{{V}_{2}}{{T}_{2}}$
or $\dfrac{400}{273} = \dfrac{500}{{T}_{2}}$
${T}_{2} = 341.25$ K = 68.25 $° C$
The temperature at which the volume becomes 500 ml the balloon will burst. So balloon burst above 68.26 $° C$.