Question

The number of molecules in one litre of water is :

(density of water $=1g/mL$)

• A. $6\times {10}^{23}/22.4$
• B. $3.33\times {10}^{25}$
• C. $3.33\times {10}^{23}$
• D. $3.33\times {10}^{24}$

Answer 1

Answer: (B)

$3.33\times {10}^{25}$

Given that :

Density of water$=$ $1g/mL$

Therefore,

Mass $=$ density$\times$ volume $=1\times 1000=1000g$

Number of moles $=$ $\frac{mass}{molarmass}$

$=\frac{1000}{18}$

$=$ $55.56$

Number of molecules $=$ $55.56$$\times 6.022\times {10}^{23}$

$=3.34\times {10}^{25}$

The correct option is B.