'A' and 'B' respectively are:
A →((1) O₃) Ethane-1,2-dicarbaldehyde + Glyoxal/Oxaldehyde; B →((1) O₃) 5-oxohexanal

Solution

Chemistry ma’am · 4 steps

Cut every C=C, put an O on each end, then match the fragments to the products given.

1. Ozonolysis rule. O₃ followed by Zn/H₂O breaks each C=C and turns both of its carbons into C=O. A carbon carrying H becomes CHO, and a carbon carrying an alkyl group becomes a ketone. In a ring, the cut opens the ring instead of splitting off a piece.
2. Finding A. Two products means two C=C. In cyclohexa-1,3-diene, cutting C1=C2 and C3=C4 frees C2–C3 as OHC–CHO (glyoxal). The rest, C4–C5–C6–C1, becomes OHC–CH₂CH₂–CHO, which is ethane-1,2-dicarbaldehyde.
3. Finding B. 5-oxohexanal is CH₃CO(CH₂)₃CHO, a single open chain with one ketone end and one aldehyde end. That comes from a ring with one C=C whose carbons carry a methyl and an H. In 1-methylcyclopent-1-ene, C1 (with the methyl) becomes CH₃C=O and C2 becomes CHO.

   Alkene	Ozonolysis products	Matches?
   Cyclohexa-1,3-diene	OHC–CHO and OHC–CH₂CH₂–CHO	A
   1-methylcyclopent-1-ene	5-oxohexanal, CH₃CO(CH₂)₃CHO	B
   Cyclopentene	pentanedial, OHC–(CH₂)₃–CHO	no
   1-methylcyclohexa-1,3-diene	OHC–CHO and 4-oxopentanal, CH₃COCH₂CH₂CHO	no

4. So. A is cyclohexa-1,3-diene and B is 1-methylcyclopent-1-ene, which is option (d).

The idea to keep. In ozonolysis, every C=C becomes two C=O. A ring with one double bond opens into one chain, and a substituent on a double-bond carbon turns that end into a ketone instead of an aldehyde.

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