Question

The number of moles of water present in a spherical droplet of radius $1.0$ cm is:
[Given: density of water in the droplet $=1.0gc{m}^{-3}$]

• A. $\frac{\pi }{18}$
• B. $\frac{2\pi }{27}$
• C. $24\pi$
• D. $\frac{2\pi }{9}$

Answer 1

Answer: (B)

$\frac{2\pi }{27}$

Volume of $H_{2}O$ droplet is $\frac{4}{3}\pi r^3$

$=\frac{4}{3}\pi (1{)}^3$

Mass of water droplet is $V\times d$

$=\frac{4}{3}\pi \times 1$

Number of moles=$\frac{4\times \pi }{3\times 18}=\frac{2\times \pi }{27}$

Hence option B is correct.