Question

7.5 ml of a gaseous hydrocarbon was exploded with 36 ml of oxygen. The volume of gases on cooling was found to be 28.5 ml, 15 ml of which was absorbed by KOH and the rest was absorbed in a solution of alkaline pyrogallol. If all volumes are measured under same conditions, the formula of hydrocarbon is

• A. C3H4
• B. C2H4
• C. C2H6
• D. C3H6

Answer 1

Answer: (B)

C2H4

Answer 2

(2)

$C_{x}H_{y} + \left( x + \frac{y}{4} \right)\overset{\quad\quad}{\rightarrow}XCO_{2} + \frac{y}{2}H_{2}O$

7.5 ml 36 ml

$36 - 7.5\left( x + \frac{y}{4} \right) + 7.5x = 28.5$

$\text{36 - 7.5 }\left( \text{15} + \frac{y}{4} \right)\text{+ 7.5 x = 28.5}$ y = 4

x = 2

So formula = C2H4