10 " mL of " a gaseous hydrocarbon is exploded with 100 " mL of " oxygen. The residual gas on cooling is found to measure 95 mL, of which 20 mL is absorbed by caustic soda and the remaining by alkaline pyrogallol. The formula of the hydrocarbon is
(a). `CH_4`.
(b). `C_2H_6`
(c). `C_2H_4`
(d). `C_2H_2`

Explanation

`C_(x)H_(y)+(x+(y)/(4))O_2toxCO_2+(y)/(2)H_2O`
`1mL(x+(y)/(4))mLxmL(y)/(2)mL`
`10mL10(x+(y)/(4))mL10xmL__`
Volume absorbed by `KOH=` volume of `CO_2`
Volume of `CO_2=20`
`x=2mL=2mol`
Volume absorbed by alkaline pyrogallol
`=` Volume of `O_2`
`=95-20=75mL`
Excess of `O_2=75mL`
Total `O_2=100mL`
Volujme of `O_2` reacted `=100-75=25mL`
`10(x+(y)/(4))=25mL`
`y=2`
Formula of hydrocarbon is `C_2H_2`.