$\mathrm{CxHy}+\left(\mathrm{x}+\frac{\mathrm{y}}{4}\right) \mathrm{O}_2 \rightarrow \mathrm{xCO}_2+\frac{\mathrm{y}}{2} \mathrm{H}_2 \mathrm{O}$
$\text { 10x } 5 \mathrm{y}$
$10 x=40$
$\mathrm{x}=4$
$5 y=50$
$\mathrm{y}=10$
$\mathrm{C}_4 \mathrm{H}_{10}$
$I.\,SeO_3^{2 - } + BrO_3^ - + {H^ + } \to SeO_4^{2 - } + B{r_2} + {H_2}O$
$II.\,BrO_3^ - + AsO_2^ - + {H_2}O \to B{r^ - } + AsO_4^{3 - } + {H^ + }$