Question

Total mass of $4.82\times {10}^{25}$ molecules of water is:

• A. 1235.71 g
• B. 3067.11 g
• C. 1440.71 g
• D. 963.21 g

Answer 1

The correct option is C 1440.71 g

Molar mass of water = 18 g
Given number of molecules of water = $4.82\times {10}^{25}$

Number of moles = $\frac{Givenmassofwater}{Molarmass}$

1 mole of a substance contains Avogadro's no. of particles in it.

$\therefore$ Total number of molecules of water = $\frac{Givenmassofwater}{Molarmassofwater}\times$ Avogadro's number

⇒ $4.82\times {10}^{25}$ = $\frac{Massofwater}{18}\times 6.022\times {10}^{23}$

⇒ Mass of water molecules = 1440.71 g