JEE Main 2025 Jan 23 Shift 2, Chemistry Q25: Properties of Alkenes

JEE Main2025Jan 23, Shift 2Chemistry

A compound 'X' absorbs 2 moles of hydrogen and 'X' upon oxidation with KMnO $_{4}$ / H $^{+}$ gives

CH $_{3}$ -CO-CH $_{3}$ , CH $_{3}$ -COOH and CH $_{3}$ -CO-CH $_{2}$ -CH $_{2}$ -COOH

The total number of $σ$ bonds present in the compound 'X' is ________.

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Solution

Counting $σ$ bonds:

C $-$ H bonds: four methyl groups contribute $4 \times 3 = 12$ H, two methylene groups contribute $2 \times 2 = 4$ H, two vinyl $= C H -$ groups contribute $2 \times 1 = 2$ H. Total $= 18$ C $-$ H $σ$ bonds.

C $-$ C $σ$ bonds: walk along the skeleton: two methyls on the first sp $^{2}$ carbon (2 bonds), the C $=$ C $σ$ component (1), methyl branch on second sp $^{2}$ carbon (1), then the chain C $-$ C $-$ C $-$ C (3 bonds), the second C $=$ C $σ$ (1), and the terminal methyl (1). Total $= 9$ C $-$ C $σ$ bonds.

$∴$ Total $σ$ bonds $= 18 + 9 = 27$ .

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JEE Main 2025 Jan 23 Shift 2, Chemistry Q25: Properties of Alkenes

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