JEE MAIN - Chemistry (2019 - 10th April Morning Slot - No. 12)

At 300 K and 1 atmospheric pressure, 10 mL of a hydrocarbon required 55 mL of O2 for complete combustion, and 40 mL of CO2 is formed. The formula of the hydrocarbon is :
C4H7Cl
C4H6
C4H8
C4H10

Explanation

CxHy + $$\left( {x + {y \over 4}} \right)$$O2 $$ \to $$ xCO2 + $${y \over 2}$$H2O

According to the above equation,

1 mL of hydrocarbon = x mL of CO2 is produced

$$ \therefore $$ 10 mL of hydrocarbon = 10x mL of CO2 is produced.

According to question,

From 10 mL of hydrocarbon 40 mL of CO2 is produced.

$$ \therefore $$ 10x = 40

$$ \Rightarrow $$ x = 4

Also from the above equation,

1 mL of CxHy react with $$\left( {x + {y \over 4}} \right)$$ mL of O2.

$$ \therefore $$ 10 mL of CxHy react with 10$$\left( {x + {y \over 4}} \right)$$ mL of O2.

According to question,

10$$\left( {x + {y \over 4}} \right)$$ = 55

$$ \Rightarrow $$ $$40 + {{10y} \over 4} = 55$$

$$ \Rightarrow $$ y = 6

$$ \therefore $$ Hydrocarbon is C4H6

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