Question

The gas leaked from a storage tank of the Union Carbide plant in Bhopal gas tragedy was:
A. Methyl isocyanate
B. Methylamine
C. Ammonia
D. Phosgene

Answer 1

Bhopal gas tragedy is a disaster that happened by a gas leak. It is considered as one of the world’s worst industrial catastrophes that occurred on the night of December $2 - 3$, $1984$ at the Union carbide India Limited (UCIL) pesticide plant in Bhopal, Madhya Pradesh, India.

Complete step by step answer:
UCIL was the Indian subsidiary of UCC, with Indian government controlled banks. UCIL factory was built to produce the pesticide Sevin using methyl isocyanate as an intermediate. The chemical process employed in the Bhopal plant had methylamine reacting with phosgene to form methyl isocyanate, which was then reacted with $1 -$ naphthol to form the final product, carbaryl.
During the night of December 2, water entered a tank containing $42{\text{tons}}$ of methyl isocyanate. The resulting exothermic reaction increased the temperature inside the tank to over ${200^ \circ }{\text{C}}$ and raised the pressure. About thirty metric tons of methyl isocyanate escaped from the tank into the atmosphere of Bhopal in $45 - 60\min$.
The atmosphere contained not only MIC, but also several other compounds like phosgene, hydrogen cyanide, carbon monoxide, hydrogen chloride, nitrogen oxides, methylamine and carbon dioxide. It caused coughing, vomiting, severe eye irritation and a feel of suffocation in people.Thus the gas leaked from the storage tank is methyl isocyanate.

Hence, the correct option is A.

Note:
The factors leading to the gas leak are:
-Storing methyl isocyanate in large tanks beyond recommended levels.
-Poor maintenance
-Failure of safety systems
-Switching off the safety systems including MIC tank refrigeration system to save money
-Plant location near to a densely populated area
-Use of dangerous pesticide manufacturing method