Question

What do the following symbols stand for ?

(a) H (b) H${}_2$ (c) 2H.

Answer 1

(a) $H$ is the symbol of hydrogen. Since there is no subscript or superscript is added to hydrogen. Hence, $H$ represents the single atom of hydrogen.
(b) $H$ atom has one electron in the valence shell. So, it combines with another hydrogen atom to complete its duplet and form a molecular hydrogen molecule. So, $H_2$ represents the molecular hydrogen.
(c) $2H$ includes the prefix 2 (two) along with a single atom of hydrogen. So, $2H$ stands for 2 moles of elemental hydrogen