Question

Potassium and sodium are not used to react with dilute hydrochloric acid or dilute sulphuric acid in labratory preparation of hydrogen

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).

For example

sodium + hydrochloric acid       sodium chloride  +   hydrogen.
2Na(s)       +     2HCl(aq)                  2NaCl(aq)      +      H2(g)