ABC26OR0035 · General Organic Chemistry
Subject: Organic Chemistry · Chapter: General Organic Chemistry · Topic: General Organic Chemistry – General · Exam: CSIR-NET JUNE 2015 · Marks: 2 · Difficulty: Hard
The correct order of heat of hydrogenation for the following compounds is 
(I) (II) (III) (IV)
(I) (II) (III) (IV)(a)I $>$ II $>$ III $>$ IV
(b)I $>$ III $>$ II $>$ IV
(c)IV > I > III > II
(d)IV $>$ II $>$ I $>$ III
Answer
Answer (as printed): B
Explanation
• More the number of α-hydrogen, lesser will be the heat of hydrogenation. α- hydrogen is the hydrogen next to the functional group (here, functional group is alkene). The hydrogens attached to the α-carbons are α-hydrogens. • Note: Trans alkene is more stable than cis alkene.
Explanation as extracted from the printed page; notation may be imperfect.