Q. $6.02\ \times \ 10^{20}$ molecules of urea are present in 100 mL of its solution. The concentration of urea solution is (Avogadro constant, $N_{A}\ = 6.02\ \times \ 10^{23}\ mol^{- 1})$
A) 0.001 M
B) 0.01 M
C) 0.02 M
D) 0.1 M
Explanation
(b)
Avogadro’s number
$N_{A}\ = \ 6.02\ \times 10^{23}$ =1 mol
$\therefore\ \ 6.02\ \times 10^{20}$ molecules = 0.001 Mol in 100 mL (0.1 L) solution
$\therefore$ Molar concentration =$\frac{mol}{volume\ in\ L\ }$
=$\frac{0.001}{0.1}$=0.01 M
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.