A compound ' X ' absorbs 2 moles of hydrogen and ' X ' upon oxidation with \(\mathrm{KMnO}_{4} \mid \mathrm{H}^{+}\)gives The total number of \(\sigma\) bonds present in the compound ' X ' is \_\_\_\_ .

JEE Main · 2025 · 23 Jan 2025 · Shift 2 · Hydrocarbons

A compound ' X ' absorbs 2 moles of hydrogen and ' X ' upon oxidation with

KMnO_{4} ∣ H^{+}

gives

The total number of

σ

bonds present in the compound ' X ' is ____ .

Answer: 27

Solution

The oxidative-cleavage products — acetone

(CH X_{3}) X_{2} C = O

, acetic acid

CH X_{3} COOH

and 4-oxopentanoic acid

CH X_{3} - CO - CH X_{2} - CH X_{2} - COOH

— fix the skeleton of X. Acetone arises from a terminal alkene carbon carrying two methyl groups,

(CH X_{3}) X_{2} C =

; acetic acid arises from a

= CH - CH X_{3}

terminus (oxidised first to acetaldehyde, then on to the acid); and 4-oxopentanoic acid is the internal fragment carrying a methyl-substituted alkene carbon (which becomes the internal ketone) at one end and a mono-substituted alkene carbon (oxidised through the aldehyde stage to

- COOH

) at the other. Reassembling these pieces around the two double bonds gives

(CH X_{3}) X_{2} C = CH - CH X_{2} - CH X_{2} - C (CH X_{3}) = CH - CH X_{3}

C X_{10} H X_{18}

diene, consistent with the uptake of exactly 2 mol

H X_{2}

on hydrogenation. This chain has 9 carbon–carbon linkages (each linkage — single or double — contributing exactly one

σ

bond) and 18 C–H bonds (matching the 18 hydrogens of

C X_{10} H X_{18}

). The total number of

σ

bonds in X is

9 + 18 = 27

JEE Main · 2025 · 23 Jan 2025 · Shift 2 · Integer answer

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JEE Main · 2025 · 23 Jan 2025 · Shift 2 · Hydrocarbons

Solution

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