Question

Phosgene is formed slowly from which one of the following on exposure to air and sunlight?
(A)- $CHC{{l}_{3}}$
(B)- ${{H}_{3}}CCl$
(C)- ${{H}_{3}}COH$
(D)- ${{C}_{2}}{{H}_{5}}Cl$

Answer 1

Hint: It was used as an anaesthetic. But soon its use was given up because of its poisonous behavior. It is widely used as an organic reagent in many chemical reactions. It has a sweet smell. It is used as an organic solvent.

Complete answer:
Let’s look at the answer.
Phosgene is a highly poisonous and colourless gas. It has an odour like that of freshly cut hay or grass. Its chemical formula is $COC{{l}_{2}}$.
$CHC{{l}_{3}}$, Chloroform is an organic compound. It was used as an anaesthetic in older times. $CHC{{l}_{3}}$ reacts slowly with oxygen in the presence of sunlight.
In reaction with oxygen in the presence of sunlight, chloroform gets oxidized and produces a highly toxic gas called phosgene.
The reaction for the above process is as follows:
$CHC{{l}_{3}}+\dfrac{1}{2}{{O}_{2}}\xrightarrow{light}COC{{l}_{2}}+HCl$
Hence, the answer for the above question is chloroform gas$CHC{{l}_{3}}$.
So, option (A) is the correct answer.
Additional Information:
Phosgene causes difficulty in breathing or shortness of breathing in a person. It can also cause nausea and vomiting. Due to these harmful effects of phosgene which is formed by chloroform, the use of chloroform was rejected.

Note: Chloroform can get oxidized into phosgene without the presence of sunlight too. In our lungs chloroform gets oxidized due to bio transformation. Chloroform gets oxidized by oxygen.