- #1

Buffu

- 849

- 146

**Question :-**The critical volume of a gas is 0.072 L mol

^{-1}. What will be the radius of the molecule in cm ?

**Answer in the book**

**:-**

##V_c = 3b \implies b = 0.024 L mol##

##\therefore## for every molecule ##b = {24 \text{cm}^3\over 6 \times 10^{23}} = 4 \times 10^{-23}\text{cm}^3## per molecule.

##\therefore 4 \times 10^{-23}\text{cm}^3 = \color{red}{4} \times \frac43 \pi r^3##

##r^3 = \left({3\over 4\pi} \times 10^{-23}\right)^{1\over3} = 1.336 \times 10^{-8}## cm

I did not get from where that 'red' 4 came in the third line ? I think volume of a sphere is just 4/3 pi r^3.

Mostly likely a mistake on behalf of the author.