Plss answer q.no 7 (b)
Q.7.(b) 20 g of sodium chloride is dissolved in 100 g of water. Calculate the percentage composition of the solution.

Dear student,
Percentage composition of a solution is expressed as mass percentage which can be calculated  as follows:
(Mass of the solute in the solution /Total mass of the solution) * 100
Here the answer is:
(20 g/100 g) *100 = 20%

Regards