Question

How many molecules of water and oxygen atoms are present in 0.9 g of water?

• A. $3.010\times {10}^{-20}$
• B. $3.010\times {10}^{22}$
• C. $3.010\times {10}^{20}$
• D. $3.010\times {10}^{-22}$

Answer 1

Answer: (B)

$3.010\times {10}^{22}$

moles of water =$\frac{0.9}{18}$= 0.05

no. of water molecules = 0.05 x6.02 x10${}^{23}$ = 3.010 x 10${}^{22}$

1 water molecule contains 1 oxygen atom

mo. of oxygen atoms = 3.010 x 10${}^{22}$