Question

What is the number of moles of hydrogen atom in 72 g of water?

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

The correct option is D

4

Given mass of water = 72 g.
Gram molecular mass of water = 18 g.
Number of moles of water in 72 g = $\frac{\text{Given mass}}{\text{Gram molecular mass}}$ = $\frac{72}{18}$ = 4 moles.

In 1 molecule of water $\left(H_{2}O\right)$, there are 2 atoms of hydrogen.

So, in 1 mole of water, there will be 2 moles of hydrogen atoms.

Hence, in 4 moles of water, 8 moles of hydrogen atoms will be present.