The Bhopal gas tragedy of 1984 was caused by the accidental leakage of which highly toxic industrial gas from a pesticide plant?

Introduction / Context:
The Bhopal gas tragedy is one of the worst industrial disasters in history. It occurred in December 1984 in Bhopal, India, when a toxic gas leaked from a pesticide manufacturing plant, causing thousands of immediate deaths and long term health problems for many more. This question tests your awareness of the specific chemical involved in this tragedy. Knowing the name of the gas is important in environmental chemistry and general awareness about industrial safety.

Given Data / Assumptions:

• The incident took place at a pesticide plant in Bhopal.
• A toxic gas used as an intermediate in pesticide production leaked.
• The options include carbon monoxide, methyl isocyanate, nitrous oxide, and hydrogen sulphide.
• We assume the context of the 1984 disaster in Bhopal, not another incident.

Concept / Approach:
The gas that leaked during the Bhopal tragedy was methyl isocyanate, often abbreviated as MIC. It is a highly toxic, volatile, and reactive compound used in the manufacture of carbamate pesticides. At the plant, water entered a storage tank containing methyl isocyanate, causing a runaway reaction, pressure buildup, and subsequent release of the gas into the surrounding area. Carbon monoxide, nitrous oxide, and hydrogen sulphide are toxic or dangerous in other contexts but are not the gases associated with this particular industrial disaster.

Step-by-Step Solution:
Step 1: Recall that the Bhopal disaster occurred at a pesticide plant operated by a multinational company. Step 2: Note that the main raw material involved was methyl isocyanate, used in the production of certain pesticide formulations. Step 3: Remember that a large amount of methyl isocyanate was stored in tanks at the site and that an uncontrolled reaction led to a massive leak. Step 4: Identify methyl isocyanate among the answer options as a highly toxic industrial chemical, unlike nitrous oxide, which is commonly used as an anaesthetic gas, or carbon monoxide, which is produced from incomplete combustion. Step 5: Conclude that methyl isocyanate is the gas responsible for the Bhopal gas tragedy.

Verification / Alternative check:
Historical accounts, investigations, and court documents about the Bhopal disaster consistently refer to methyl isocyanate as the leaked gas. Survivors, medical studies, and environmental reports also describe exposure symptoms characteristic of this compound, such as severe respiratory damage and eye irritation. No reliable source states that carbon monoxide, nitrous oxide, or hydrogen sulphide were the primary compounds released in the main accident, although other gases may have been present in minor amounts. This strong and consistent evidence confirms methyl isocyanate as the correct answer.

Why Other Options Are Wrong:
Carbon monoxide is a toxic gas produced by incomplete combustion of fuels, but it is not the chemical stored in large tanks at Bhopal and is not the gas named in connection with that tragedy. Nitrous oxide is used in medicine and industry and is not associated with the Bhopal accident. Hydrogen sulphide is a poisonous gas associated with sewage and petroleum processing, but the main Bhopal leak was not hydrogen sulphide. These gases can cause poisoning but are not the ones implicated in the 1984 Bhopal disaster.

Common Pitfalls:
Some learners may confuse the Bhopal gas tragedy with other industrial or environmental incidents and choose a more familiar toxic gas such as carbon monoxide or hydrogen sulphide. Others may recognise the abbreviation MIC but forget the full name methyl isocyanate. To avoid mistakes, associate Bhopal directly with MIC and remember that the tragedy involved a pesticide intermediate, not a combustion product or sewer gas.

Final Answer:
The Bhopal gas tragedy was caused by the leakage of methyl isocyanate from a pesticide plant.