Question

Number of atoms of He in 100 u of He (atomic weight of He = 4u) are

• A. 25
• B. 50
• C. 100
• D. $100\times 6\times {10}^{-23}$

Answer 1

Answer: (A)

$\therefore$ $4u=1\text{He}\text{atom}$ $1u-\frac{1}{4}\text{He}\text{atom}$ $\therefore$ $100u=\frac{1\times 100}{4}=25\text{atoms}$