Chloroform is stored in closed dark coloured bottle completely filled so that
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → phosgene is not produced.
Chloroform is slowly oxidised by the oxygen of air in the presence of light to an extremely poisonous gas, phosgene (carbonyl chloride):
\( \displaystyle \ce{2CHCl3 + O2} \xrightarrow{\text{light}} \ce{2COCl2 + 2HCl} \)
Both conditions for this reaction are removed during storage:
A dark coloured bottle keeps out light.
A closed bottle filled to the top leaves no air (oxygen) inside.
So chloroform is stored this way so that phosgene is not produced.
Why the other options are incorrect
Option (2) it does not spill — Incorrect. Spilling has nothing to do with the colour of the bottle or with filling it completely.
Option (3) it does not evaporate — Incorrect. Closing the bottle is enough to stop evaporation; the dark glass and the full bottle are there to keep out light and air.
Option (4) it is not visible — Incorrect. The dark glass blocks light because light starts the oxidation, not to hide the liquid.
NCERT (2026-27 edition):
Trichloromethane (Chloroform)
