Question

6.4 g of oxygen will contain ______ number of oxygen molecules.

• A. $6.023\times {10}^{23}$
• B. $6.023\times {10}^{22}$
• C. $1.2046\times {10}^{23}$
• D. $1.2046\times {10}^{22}$

Answer 1

The correct option is C $1.2046\times {10}^{23}$

Molar mass of oxygen $=32g/mol$

Moles in 6.4 g oxygen $=\frac{6.4}{32}=0.2$ moles
Number of $O_2$ molecules in 0.2 mole $=0.2\times 6.023\times {10}^{23}$ $=1.2046\times {10}^{23}$ molecules