hydrogen

Water can be reduced to oxygen and hydrogen by electrolysis.

水通过电解可以分解为氧和氢。

Water is a compound containing the elements hydrogen and oxygen.

水是含有氢元素和氧元素的化合物。

The first bubbles to escape from the liquid are a mixture of air and hydrogen.

从该液体中最先逸出的气泡是空气和氢的混合物。