Question

what is relation between an atom and molecule

Answer 1

That means, hydrogen can combine with oxygen to create a compoundcalled 'Water'. A compound is 'impure', that means it contains more than one type of atom. When a group of atoms combine, they create a molecule. This molecule is the smallest fundamentalunit that can take part a reaction

Answer 2

Atoms make up molecules. You need at least two atoms to make a molecule. Two oxygen atoms will make one oxygen molecule. Two hydrogen atoms and one oxygen atom will make one molecule of water. Atoms are the smallest component of an element