Question

Bhopal gas tragedy was caused by:
A: CFC
B: $CH_3NCO$
C: $C_2H_3N$
D: $CH_3CN$

Answer 1

Hint: On December 3, 1984, a poisonous gas got leaked out from Union Carbide India Limited (i.e. UCIL’s) pesticide factory located in Bhopal (Madhya Pradesh) as a result of which thousands of people lose their lives. This particular incident is known as either the Bhopal disaster or Bhopal gas tragedy.

Complete answer:
Union Carbide India's Bhopal facility housed three storage tanks each containing 68,000-litre liquid methyl isocyanate (MIC). These tanks were named as E610, E611, and E619. One of these tanks (i.e. E610) lost its ability to carry nitrogen gas pressure, due to which liquid MIC could not be pumped out. In accordance with the rules or regulations, each of the tanks was not allowed to be filled with more than 30 tonnes of liquid MIC. However, this tank comprised approximately 42 tonnes. This failure forced UCIL to stop MIC production in Bhopal and the plant was temporarily shut for maintenance purposes. As per the reports, by December 2, 1984 , water had entered the malfunctioned tank, which resulted in a runaway chemical reaction. The pressure in the tank augmented to almost five times by night. By midnight, the workers present in the MIC area started to feel the effects of MIC gas. The chemical reaction occurring in the tank reached a critical state. Around 30 tonnes of MIC escaped from the tank into the air within one hour.
MIC, with the molecular formula of $CH_3NCO$, is a colourless, flammable, and a low boiling point $(390^0C)$ liquid with a sharp odour. It is highly toxic and causes immense hazards to human health. It is mainly used in the manufacturing of plastics, polyurethane foam and pesticides.

Hence, the correct answer is option B: $CH_3NCO$ i.e. methyl isocyanate.

Note: MIC is a colourless liquid normally used for the manufacturing of pesticides. MIC is safe only if maintained properly. This chemical is highly reactive to heat. When it is exposed to water, the compounds present in it starts reacting with one another causing a heat reaction.