Question

6.02 × 10²⁰ molecules of urea are present in 100 mL of its solution. The concentration of solution is

(a) 0.001 M

(b) 0.1 M

(c) 0.02 M

(d) 0.01 M

Answer 1

Ans. (d) 0.01 M

Sol. no of moles = no of molecules / N_A

n = 6.02 x 10²⁰ / 6.02 x 10²³ 

n = 10^-3

Molarity = no of moles / volume of solution(L)

M= 0.001/100 x 1000 

M = 0.01M