(i) Maximum stretching capacity $=400\times \frac{5}{4}=500$ ml
$\frac{{\mathrm{V}}_1}{{\mathrm{T}}_1}=\frac{{\mathrm{V}}_2}{{\mathrm{T}}_2}$
or $\frac{400}{273}=\frac{{\mathrm{V}}_2}{313}$
${\mathrm{V}}_2=458.61$ 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 $°\mathrm{C}$ .
(ii) $\frac{{\mathrm{V}}_1}{{\mathrm{T}}_1}=\frac{{\mathrm{V}}_2}{{\mathrm{T}}_2}$
or $\frac{400}{273}=\frac{500}{{\mathrm{T}}_2}$
${\mathrm{T}}_2=341.25$ K = 68.25 $°\mathrm{C}$
The temperature at which the volume becomes 500 ml the balloon will burst. So balloon burst above 68.26 $°\mathrm{C}$.