Hydrocarbons 2 Question 30
30. Which one of the following has the smallest heat of hydrogenation per mole?
$(1993,1 \mathrm{M})$
(a) 1-butene
(b) trans-2-butene
(c) cis-2-butene
(d) 1, 3-butadiene
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Answer:
Correct Answer: 30. (d)
Solution:
- Among alkenes-heat of hydrogenation depends on :
(a) The number of double bonds-greater, greater the amount of heat evolved in hydrogenation.
Hence, 1, 3-butadiene has highest heat of hydrogenation among these.
(b) Relative stability of alkenes-greater the stability, smaller the heat evolved in hydrogenation. trans-2-butene is most stable among three given butenes, has least heat of hydrogenation.
