Question

why is the volume of gas collected at one electrode double than the other?

Answer 1

The compound that is most common would be water 1 part Oxygen 2 parts Hydrogen. Hydrogen is the gas that is double.

Explanation:

When the compound water ( Hydrogen Oxide) #H_2O# breaks apart it creates twice the volume of Hydrogen and the Volume of Oxygen

# 2 H_2O rarr 2 H_2 + 1 O_2

The two gases Hydrogen and Oxygen are produced in a 2:1 ratio.