Question

What do the following symbols stand for 1) H ;2) H2 ;3)2H

Answer 1

H means 1 atom of hydrogen
H2 means 1 molecule or 2 atoms of hydrogen
2H means 2 molecule of hydrogen

Answer 2

Explanation:

An atom is defined as the simplest unit of matter which cannot be broken down. Elements contain atoms. Example: Hydrogen (H), Carbon (C) etc..

Molecule is defined as the cluster of atoms which chemically combine together. These can be of compounds (different atoms) as well as of elements (same atoms). Example: $CO_2$ , $H_2$ etc..

For the given options:

Option 1: H

This is defined as 1 atom of hydrogen element.

Option 2: $H_2$

This is defined as 1 molecule of hydrogen gas or 2 atoms of hydrogen element are present in 1 molecule.

Option 3: 2H

This is defined as 2 atoms of hydrogen element.