Question

Potassium is not used for preparation of hydrogen from water . Why?

Answer 1

) Potassium, sodium, lithium and calcium all react violently
with dilute sulfuric acid and dilute hydrochloric acid.
It is dangerous to put thesemetals into an acid.
The reaction is similar to the reaction with water,
forming the metal salt (either sulfate or chloride) plus H2(g).