Smack is chemically known as:

The correct answer is Option (4) → Diacetylmorphine

Smack is another name for heroin. Heroin belongs to the opioids, the drugs that bind to opioid receptors in the central nervous system and the gut. It is made by acetylation of morphine, which is taken from the latex of the poppy plant Papaver somniferum. It is a depressant and slows down body functions.

(1) Cannabinoid — Incorrect. Cannabinoids are a different group of drugs. They come from the flower tops of Cannabis sativa (marijuana, hashish, charas, ganja) and act on receptors in the brain.

(2) Barbiturates — Incorrect. These are sedative drugs used as medicines for conditions such as insomnia. They are not heroin.

(3) Amphetamines — Incorrect. These are stimulant drugs used as medicines for conditions such as depression. They are not heroin.

(4) Diacetylmorphine — Correct. This is the chemical name of heroin, or smack.

Note: A similar question was also asked in CUET (UG) 2024 on 15-05-2024 (Slot 1).

NCERT Extract:
Drugs and Alcohol Abuse – “Opioids are the drugs, which bind to specific opioid receptors present in our central nervous system and gastrointestinal tract. Heroin (Figure 7.7), commonly called smack is chemically diacetylmorphine which is a white, odourless, bitter crystalline compound. This is obtained by acetylation of morphine (Figure 7.7), which is extracted from the latex of poppy plant Papaver somniferum (Figure 7.8).”