JEE Main 2026 — Apr 2, Shift 1 — Chemistry solution

JEE Main2026Apr 2, Shift 1Chemistry

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 _____.

Your answer

Solution

General combustion equation for an alkane $C_{n} H_{2 n + 2}$ :

$C_{n} H_{2 n + 2} + (\frac{3 n + 1}{2}) O_{2} \to n C O_{2} + (n + 1) H_{2} O$

Set the oxygen coefficient equal to $8$ :

$\frac{3 n + 1}{2} = 8 \Rightarrow 3 n + 1 = 16 \Rightarrow n = 5$

The alkane is $C_{5} H_{12}$ , so the sum of carbon and hydrogen atoms is $5 + 12 = 17$ .

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