In the given reaction,
The number of π electrons present in the product 'P' is _________.

Solution

Chemistry ma’am · 4 steps

Two cyclohexanones join and lose water, so P keeps one C=O and gains one C=C. Count those two π bonds.

1. Enolate forms. Cyclohexanone has α-hydrogens, so OH⁻ removes one and gives an enolate. This enolate attacks the C=O carbon of a second cyclohexanone molecule (self-aldol addition).
2. Heat removes water. The aldol product, 2-(1-hydroxycyclohexyl)cyclohexanone, loses H₂O on heating. A C=C forms in conjugation with the C=O, giving the α,β-unsaturated ketone.

   2 C₆H₁₀O →(OH⁻, Δ) C₁₂H₁₈O + H₂O

3. Count π electrons. P is 2-cyclohexylidenecyclohexanone. It has one C=O and one C=C, that is 2 π bonds, and each π bond holds 2 electrons: 2 × 2 = 4. The lone pairs on oxygen are non-bonding and are not counted.
4. So. The number of π electrons in P is 4.

The common slip: 2. Counting π bonds instead of π electrons gives 2. Each π bond carries 2 electrons, so double it.

The idea to keep. Aldol condensation always ends in an α,β-unsaturated carbonyl: the C=O survives and one new C=C appears. For π electrons, count π bonds and multiply by 2.

Answer from the NTA final answer key. Solution by PrepWiser.