Question

why are sodium matter and potassium metal is put in the kerosene?​

Answer 1

sodium metal and potassium metal are highly reactive metals

they react vigorously when exposed to oxygen hence, are kept in kerosene.

Answer 2

$\huge\bf{\pink{\mid{\overline{\underline{Answer\:with\: Explanation}}}\mid}}$

$\bold{\small{\color{blue}{Reason:}}}$

Sodium metal and potassium metal react with water producing a lot of heat. As a result, the hydrogen evolved catches fire because it is very inflammable gas. They cannot be kept in air also because air contains moisture for water vapours. These are kept under kerosene to avoid contact with both air and water.

$\bold{\small{\color{red}{Reactions\:with\:water:}}}$

$2Na(s) + 2H_2O(l) ----> 2NaOH(aq) + H_2(g)$

$2K(s) + 2H_2O(l) ----> 2KOH(aq) + H_2(g)$

$\bold{\small{\color{red}{Reactions\:with\:oxygen:}}}$

$2Na(s) + O_2(g) ----> 2Na_2O(s)$

$2K(s) + O_2(g) ----> 2K_2O(s)$