Which of the following gases is consistently seen to be most abundant in a volcanic eruption?

Option 3 : Water vapour

The correct answer is Water vapour.

• Water Vapour- It is consistently seen to be the most abundant in a volcanic eruption. 
• It occurs when lava and gas are discharged from the vent of the volcano.
• The eruption majorly emits water vapor into the atmosphere. But other gases like-Carbon dioxide, Sulphur Dioxide, Hydrogen Sulfide are also emitted.
• 'Glowing avalanche' is the most dangerous type of volcanic eruption.
• The magma which is freshly erupted forms a hot pyroclastic flow. This flow generally has a temperature of up to 1,200 degrees.
• The flow sometimes takes a speed of up to several hundred kilometers per hour. It can reach as far as 40 km from the original disaster site.