Question

One mole of an alkane (\(x\)) requires 8 mole oxygen for complete combustion. Sum of number of carbon and hydrogen atoms in the alkane (\(x\)) is ______.

Answer 1

Correct Answer: 17

Concept: General formula of an alkane: \[ C_nH_{2n+2} \] Combustion reaction: \[ C_nH_{2n+2} + \left(\frac{3n+1}{2}\right)O_2 \rightarrow nCO_2 + (n+1)H_2O \]
Step 1:Use given oxygen requirement} Given: \[ \frac{3n+1}{2} = 8 \]
Step 2:Solve for \(n\)} \[ 3n+1 = 16 \] \[ 3n = 15 \] \[ n = 5 \] Thus the alkane is: \[ C_5H_{12} \]
Step 3:Find total atoms} \[ C + H = 5 + 12 = 17 \] \[ \boxed{17} \]