Question

The percentage of an element $ M $ is $ 53 $ in its oxide of molecular formula $ {{M}_{2}}{{O}_{3}} $ . Its atomic mass is about

• A. 45
• B. 9
• C. 18
• D. 36
• E. 27

Answer 1

Answer: (E)

Percentage of element M in $ {{M}_{2}}{{O}_{3}}=53 $
Let the atomic mass of $ M=x $
Mass of $ M $ in $ {{M}_{2}}{{O}_{3}}=2x $
Total atomic mass of $ {{M}_{2}}{{\text{O}}_{3}}=2x+16\times 3 $
$ =2x+48 $ Percentage of an element $ =\frac{Mass\text{ }of\text{ }an\text{ }element\text{ }in\text{ }a\text{ }compound}{Total\text{ }mass\text{ }of\text{ }compound}\times 100 $
$ 53=\frac{2x}{2x+48}\times 100 $
$ 53(2x+48)=200x $
$ x=27 $