Q. Consider the following :

1. Pyroclastic debris
2. Ash and dust
3. Nitrogen compounds
4. Sulphur compounds

How many of the above are products of volcanic eruptions? (UPSC Prelims 2024)
Answer: All four
Notes: The correct answer is [D] All four. Volcanic eruptions release a diverse range of materials including solids, molten rock, and various gases into the atmosphere and surrounding landscape.

• Pyroclastic debris (Correct): This refers to the "fire-broken" fragments of rock, glass, and solidified lava ejected during an explosive eruption. It ranges in size from small pebbles (lapilli) to massive volcanic bombs.
• Ash and dust (Correct): These are the finest particles of pulverized rock and glass (less than 2mm in diameter). Volcanic ash can be carried by winds for thousands of kilometers, affecting global climates and aviation.
• Nitrogen compounds (Correct): Volcanoes emit various nitrogen-based gases, primarily in the form of Nitrogen (N₂) and smaller amounts of ammonia or nitrogen oxides. While less abundant than water vapor or CO₂, they are a standard component of volcanic degassing.
• Sulphur compounds (Correct): Volcanoes are a major natural source of sulphur. They release Sulphur dioxide (SO₂) and Hydrogen sulphide (H_2S). SO₂ is particularly significant as it reacts in the atmosphere to form sulphate aerosols, which can reflect solar radiation and cool the Earth's surface.

Beyond these four, the most abundant gas released is water vapor, followed by carbon dioxide. The specific composition of these products often depends on the type of magma and the intensity of the eruption.