Question

Number of atoms of $He$ in $100$ amu of $He$ (atomic wt. of $He$ is $4$) are :

• A. 25
• B. 100
• C. 75
• D. $100 \times 6 \times 10^{23}$

Answer 1

Answer: (A)

25

Answer 2

$100$ amu of $He = \frac{100}{4}$ atoms of $He$ $= 25$ atoms. [$1$ a.m.u. = mass of one proton (approx.)]