Question

How many water molecules are there in one drop of water (volume of 1 drop of water = $0.0018$ ml) at room temperature?

• A. $6.023\times {10}^{19}$
• B. $1.084\times {10}^{18}$
• C. $6.023\times {10}^{23}$
• D. $4.8\times {10}^{16}$

Answer 1

The correct option is A $6.023\times {10}^{19}$

At room temperature, we have density = 1g/ml

so, mass of 1 drop of water = $.0018\times 1=0.0018g$

we have,

18 g of water have no. of molecules = $6.023\times {10}^{23}$

so, number of molecules present in 0.0018g of water = $\frac{6.023\times {10}^{23}}{18}\times 0.0018=6.023\times {10}^{19}$ water molecules