Question

Which of the following correctly represents 360 g of water?

• A. 56 g
• B. 112 g.
• C. 42 g
• D. 28 g

Answer 1

Answer: (B), (D)

The correct options are
B

112 g.

D

28 g

The gram molecular mass of water is 18 g.
Also, number of molecules in 1 mole of ${\text{H}}_2\text{O}$ = $6.022\times {10}^{23}$

We know that number of moles
= $\frac{\text{Mass in grams}}{\text{Gram molecular mass}}$

Number of moles of water in 360 g = $\frac{360}{18}=20$ mol.
Number of ${\text{H}}_2\text{O}$ molecules in 1 mole (18 g) = $6.022\times {10}^{23}$
So, number of molecules in 360 g of ${\text{H}}_2\text{O}$ = $\frac{360}{18}\times 6.022\times {10}^{23}$
= $1.2044\times {10}^{25}$ molecules of ${\text{H}}_2\text{O}$