Q. Number of atoms of He in 100 u of He (atomic weight of He is 4) are
A) 25
B) 100
C) 50
D) $100 \times 6 \times 10^{- 23}$
Explanation
(a)
$\because 4\ u = 1\ He\ atom$
$\therefore 1\ u = \frac{1}{4}He\ atom$
Hence, 100 u = $\frac{1 \times 100}{4} = 25\ atoms$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.