The external energy level of an atom of an element has the structure ns2np2.

The external energy level of an atom of an element has the structure ns2np2. It forms a volatile compound with hydrogen in which 25% is hydrogen.

The electronic configuration corresponds to an element of the fourth group of the main subgroup of the Periodic Table of Chemical Elements. In this group, volatile compounds with hydrogen can form carbon, silicon and germanium. Judging by the high mass fraction of hydrogen in the compound, the sought element should be light. Of these elements, carbon is the lightest. Let’s find the mass fraction of hydrogen in methane – the simplest hydrogen carbon compound.

w (H) = 4 * M (H) / M (CH4) = (4 * 1) / 16 = 0.25 = 25% – coincides with that given in the conditions.

The answer is carbon.