What is formed when chloroform is slowly oxidised by air in the presence of light?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Phosgene
In light, air slowly oxidises chloroform to carbonyl chloride (phosgene), an extremely poisonous gas:
\( \displaystyle \ce{2CHCl3 + O2} \xrightarrow{\text{light}} \ce{2COCl2 + 2HCl} \)
NCERT (2026-27 edition):
6.8.2 Trichloromethane (Chloroform) – “… Chloroform is slowly oxidised by air in the presence of light to an extremely poisonous gas, carbonyl chloride, also known as phosgene. It is therefore stored in closed dark coloured bottles completely filled so that air is kept out.”