Alkali metals react vigorously with cold water resulting in the displacement of ______.

hydrogen

The correct answer is option 2. hydrogen.

Alkali metals react vigorously with cold water resulting in the displacement of hydrogen.

When alkali metals such as lithium, sodium, or potassium react with cold water, they undergo a vigorous reaction in which hydrogen gas is produced. This reaction is highly exothermic and generates heat, often leading to the formation of hydrogen gas bubbles and the formation of metal hydroxides.