Question

The element chlorine consists of a mixture of $75.53$ and $24.47$ having a mass of $34.97$ amu and $36.95$ amu, respectively. The atomic weight of chloride is:

• A. 35.25
• B. 35.45
• C. 36.25
• D. 36.45

Answer 1

Answer: (B)

At. wt. of chlorine
$=\frac{\text{ Abundance }\times \text{ mass }+\text{ Adundance }\times \text{ mass }}{100}$
Given, abundance of $C{l}^{35}$ isotope $=75.53$
Mass of $C{l}^{35}$ isotope $=34.97$
Abundance of $C{l}^{37}$ isotope $=24.47$
Mass of $C{l}^{37}$ isotope $=36.95$
$\therefore$ At. wt. of chlorine
$=\frac{34.97\times 75.53+24.47\times 36.95}{100}$
$=\frac{3545.45}{100}$
$=35.45$