Choose the correct statements about chloroform.
(A) It slowly reduces in air in the presence of sunlight to form phosphene gas.
(B) It should be stored in closed dark coloured bottles completely filled to keep air out.
(C) When exposed to sunlight in the presence of air, it forms a gas, phosgene.
(D) Chronic chloroform exposure causes damage to liver.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (B), (C) and (D) only
Chloroform is slowly oxidised by air in the presence of light to the very poisonous gas phosgene (carbonyl chloride):
\( \ce{2CHCl3} \) + \( \ce{O2} \) → \( \ce{2COCl2} \) + 2HCl
(A) It slowly reduces in air in the presence of sunlight to form phosphene gas — False. Chloroform is oxidised, not reduced, and the gas is phosgene (\( \ce{COCl2} \)); phosphene is not the product.
(B) Stored in closed dark coloured bottles completely filled to keep air out — True. Dark bottles cut off light and filling them completely removes air, the two conditions for phosgene formation.
(C) On exposure to sunlight in the presence of air it forms phosgene — True. This is the oxidation shown above.
(D) Chronic chloroform exposure causes damage to liver — True. Chloroform is metabolised to phosgene in the liver; long exposure damages the liver and the kidneys.
NCERT (2026-27 edition):
Trichloromethane (Chloroform) – “… Chronic chloroform exposure may cause damage to the liver (where chloroform is metabolised to phosgene) and to the kidneys, and some people develop sores when the skin is immersed in 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.”