What is the significance of molecular formula

The molecular formula of a compound represents molecular mass of the substance. For example, the molecular mass of water molecule (H2O) is 18u.

(iv) The molecular formula of any compound gives the name, and actual number of atoms of each kind present in one molecule of the substance. For example, the formula for water is H2O. This means that every molecule of water is made up of 2 atoms of hydrogen and one atom of oxygen.

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.

they are made of gases.

they have a spherical shape.

they make energy through fusion.