JEE Main Chemistry Question (2026) — Solution

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The general formula of an alkane is C_n H_ 2n+2 . The balanced chemical equation for the complete combustion of an alkane is: C_n H_ 2n+2 + ( 3n+1 2 ) O_2 n CO_2 + (n+1) H_2O Given that 1 mole of the alkane requires 8 moles of oxygen for complete combustion, we equate the stoichiometric coefficient of O_2 to 8: 3n+1 2 = 8 3n + 1 = 16 3n = 15 n = 5 The molecular formula of the alkane is C_5H_ 12 . The number of carbon atoms is 5 and the number of hydrogen atoms is 12. Sum of the number of carbon and hydrogen atoms = 5 + 12 = 17. Answer: 17