In Indian environmental disaster history, which poisonous gas was accidentally released during the 1984 Bhopal gas tragedy, causing thousands of deaths and injuries?

Introduction / Context:
The Bhopal gas tragedy of 1984 is considered one of the world's worst industrial disasters and is a key topic in Indian environmental and general knowledge. Understanding which specific gas was involved helps students appreciate the importance of industrial safety and chemical hazard management. This question asks you to identify the poisonous gas that leaked from the pesticide plant in Bhopal and caused massive loss of life and long term health problems.

Given Data / Assumptions:

• The incident referred to is the Bhopal gas tragedy in 1984.
• The event involved a leak of a toxic industrial chemical from a pesticide plant.
• Several gases are listed as options, including methane, nitrous oxide, methyl isocyanate, and cyanogen.
• We assume standard historical accounts of the tragedy.

Concept / Approach:
The pesticide plant in Bhopal stored large quantities of methyl isocyanate, a highly toxic and volatile compound used in the manufacture of insecticides. Due to failures in maintenance and safety systems, water entered a storage tank, causing a violent reaction and release of methyl isocyanate gas into the surrounding areas. The gas spread over nearby densely populated regions, leading to acute poisoning, respiratory failure, and long term health issues. Therefore, the correct answer must be methyl isocyanate, not other common gases listed.

Step-by-Step Solution:
Step 1: Recall that the Bhopal disaster involved a pesticide manufacturing plant operated by a multinational company. Step 2: Remember that the main chemical stored in the tank that leaked was methyl isocyanate, often abbreviated as MIC. Step 3: Recognise that this substance is extremely toxic even at low concentrations and can cause severe lung damage. Step 4: Compare this information with the options and identify methyl isocyanate as the gas involved. Step 5: Select methyl isocyanate as the correct answer for the gas released in the tragedy.

Verification / Alternative check:
Accounts of the tragedy in environmental science books, documentaries, and official reports all name methyl isocyanate as the gas that escaped. They describe how inadequate safety systems, poor maintenance, and lack of proper alarms allowed a large amount of this gas to be released. No source identifies methane, nitrous oxide, or cyanogen as the main gases in the accident. This consistent documentation across many reliable references confirms that methyl isocyanate is the correct chemical associated with the Bhopal gas tragedy.

Why Other Options Are Wrong:
Methane is a relatively simple hydrocarbon gas and is flammable but was not the main toxic gas in this incident. Nitrous oxide is sometimes called laughing gas and is used in medicine and industry but is not associated with the Bhopal disaster. Cyanogen is a toxic gas, but it was not the primary chemical stored and released in the Bhopal plant. These gases do not match the documented accounts of the tragedy, which specifically point to methyl isocyanate.

Common Pitfalls:
Some students may confuse methyl isocyanate with other cyanide related compounds or may simply pick any gas with a dangerous sounding name. Others might choose methane because it is a familiar gas, even though it was not the one involved. To avoid these mistakes, it is important to remember that methyl isocyanate, abbreviated MIC, is directly linked to the Bhopal gas tragedy. Keeping this association clear helps in both exams and in understanding the significance of the disaster in environmental history.

Final Answer:
The poisonous gas released during the Bhopal gas tragedy was methyl isocyanate.