Question

How many water molecules are there in a drop of volume 0.05 mL? (Density of water is 1 g/mL)

• A. $1.67\times {10}^{21}$
• B. $1.67\times {10}^{22}$
• C. $1.67\times {10}^{23}$
• D. $1.67\times {10}^{24}$

Answer 1

The correct option is A $1.67\times {10}^{21}$

mass of 1 drop $=0.05\times 1g=0.05g$

No. of water molecules = moles $\times 6.02\times {10}^{23}$

= $\frac{0.05}{18}\times 6.02\times {10}^{23}$

= $1.67\times {10}^{21}$