Question

The atomic mass of carbon is 12 g and that of oxygen is 16 g. How many grams of carbon contains as many atoms as 50 g of oxygen?

• A. 50.0 g
• B. 37.5 g
• C. 12.1 g
• D. 15.9 g

Answer 1

The correct option is B 37.5 g

Given mass of oxygen = 50 g
Gram atomic mass of carbon = 12 g
Gram atomic mass of oxygen = 16 g

Let the required mass of carbon be $x$ grams.
Number of atoms of carbon = number of atoms of oxygen.

Number of atoms = $\frac{\text{Mass of element}}{\text{Gram atomic mass}}\times \text{Avogadro's number}$

$\frac{x}{12}\times 6.022\times {10}^{23}=\frac{50}{16}\times 6.022\times {10}^{23}$
$\Rightarrow x=\frac{50\times 12}{16}=\frac{75}{2}=37.5$

Hence, the required mass of carbon is 37.5 grams.