The compound with molecular formula C6H6, which gives only one monobromo derivative and takes up four moles of hydrogen per mole for complete hydrogenation has electrons.
Answer
8 or 6
Solution
C6H6: 4 degrees of unsaturation; 4 mol H2 ⇒ two C C (no ring). One monobromo product ⇒ symmetrical hexa-2,4-diyne:
[figure]
electrons =4 2=8
(Benzene also gives only one monobromo product: 6 electrons.)
Answer: 8 or 6