Question

Oxygen contains $90\%O^{16}$ and $10\%O^{18}$ . Its atomic mass is

• A. 16.2
• B. 17.4
• C. 17
• D. 16.5

Answer 1

Answer: (A)

Oxygen have $90\%O^{16}$ and $10\%O^{18}$
$\therefore$ Atomic mass
$=\left[\frac{90}{100}\times 16+\frac{10}{100}\times 16\right]$
$=\frac{1440+180}{100}=\frac{1620}{100}=16.2$