An antiseptic dettol is a mixture of two compounds 'A' and 'B' where A has 6π electrons and B has 2π electrons. What is 'B'?

Solution

Chemistry ma’am · 3 steps

Dettol is chloroxylenol plus terpineol, so count pi electrons to tell the two partners apart.

1. What dettol contains. Dettol is a mixture of chloroxylenol and terpineol. Bithionol and chloramphenicol are not part of it.
2. Count pi electrons. Each C=C or C=O double bond holds one pi bond, which is 2 pi electrons. A benzene ring has three such bonds, so it carries 6 pi electrons.

   Compound	Pi system	Pi electrons	In dettol?
   Chloroxylenol	one benzene ring	6	yes, this is A
   Terpineol	one ring C=C, no aromatic ring	2	yes, this is B
   Bithionol	two benzene rings	12	no, used in soaps
   Chloramphenicol	benzene ring, NO₂ and C=O	more than 6	no, an antibiotic

3. So. Chloroxylenol is A with 6 pi electrons, and terpineol is B with just one double bond, 2 pi electrons. The answer is (b).

The idea to keep. Remember dettol as chloroxylenol plus terpineol. One is an aromatic phenol, the other is a terpene alcohol with a single C=C.

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