JEE Chemistry 2025 Question with Solution

Given: The compound shown undergoes complete ozonolysis.

Find: The number of optically active products formed.

Principle: Ozonolysis cleaves each $\mathrm{C=C}$ bond to give carbonyl compounds. After cleavage, each product must be checked for the presence or absence of a chiral center.

From the solution working, the organic products formed on complete ozonolysis are:

1. $\mathrm{CH_3CHO}$ (ethanal) — achiral
2. A chiral aldehyde product
3. $\mathrm{OHC{-}CHO}$ (glyoxal) — achiral
4. Another chiral dialdehyde product
5. $\mathrm{OHC{-}CHO}$ (glyoxal) — achiral

Now examine optical activity:

• Ethanal is achiral.
• Glyoxal is achiral.
• The two remaining aldehydic products contain asymmetric carbon centers, so they are optically active.

Thus, the number of optically active products is $2$.

Therefore, the correct option is B.

Given: A chiral polyene is subjected to complete ozonolysis.

Find: How many products are optically active.

Step 1: In ozonolysis, every $\mathrm{C=C}$ bond is cleaved and converted into aldehyde or ketone groups.

Step 2: The extracted solution states that after cleavage the products include ethanal, glyoxal, and two products having asymmetric carbon centers.

Step 3: Optical activity depends on chirality, not merely on the number of fragments formed.

• Ethanal has no chiral center, so it is not optically active.
• Glyoxal has no chiral center, so it is not optically active.
• The other two products are chiral, so each is optically active.

Conclusion: Exactly $2$ products are optically active. Hence, the correct option is B.