Q.

80 mL of a hydrocarbon on mixing with 264 mL of oxygen in a closed U-tube undergoes complete combustion. The residual gases after cooling to 273 K occupy 224 mL. When the system is treated with KOH solution, the volume decreases to 64 mL. The formula of the hydrocarbon is:   [2026]

1 C4H10  
2 C2H6  
3 C2H2  
4 C2H4  

Ans.

(3)

CxHy+(g)(x+y4)O2(g)xCO2+(g)y2H2O()

t=0802640-t=tfinal-264-80(x+y4)80x-

264-80(x+y4)+80x=224

264-80y4=224

40=80y4y=2

264-80(x+y4)=64

264-80(x+12)=64

264-80x-40=64

x=2