Heat of hydrogenation of cyclohexene (g) is – 29 kcal $m o l^{- 1}$ , observed heat of hydrogenation of cyclohexa-1, 3-diene (g) is – 56 kcal $m o l^{- 1}$ and resonance energy of benzene (g) is –36 kcal/mol.

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The observed heat of hydrogenation of benzene (g) is -51 kcal $m o l^{- 1}$

The magnitude of resonance energy of cyclohexa-1, 3-diene (g) is 2 kcal $m o l^{- 1}$

The observed heat of hydrogenation of benzene (g) is –123 kcal $m o l^{- 1}$

The theoretical heat of hydrogenation of benzene (g) is –87 kcal $m o l^{- 1}$

answer is A, B, C.

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Detailed Solution

$Δ_{Hyd} H_{1} {= – 29 kcal mol}^{-1}$

${(Δ_{Hyd} H)}_{C_{6} H_{8} T h e o} {= – 29×2= –58 kcal mol}^{-1}$

${(Δ_{H y d} H)}_{C_{6} H_{6}, T h e o} = - 29 \times 3 = - 87 k J m o l^{- 1}$

${(Δ_{Hyd} H)}_{C_{6} H_{B} O b s} {= –56 kcal mol}^{-1}$

$RE = –58 – (–56) {= –2 kcal mol}^{-1}$

$R E = - 36 k c a l m o l^{- 1}$

${(Δ_{H y d} H)}_{C_{6} H_{6} O b s} = - 87 + 36 = - 51 k c a l m o l^{- 1}$

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