Multiple choice

Which of the following is the most abundant gas emitted from volcanoes?

  1. Water vapour

  2. Helium

  3. Sulphur dioxide

  4. Carbon dioxide

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Water vapor (H2O) constitutes about 60-90% of all volcanic gas emissions by volume. While CO2 and SO2 are significant, water vapor is by far the most abundant. Helium is present only in trace amounts. This makes option A correct.