Answer : The concentration of water vapor in a sample of air is, ![1.2\times 10^3ppm](https://tex.z-dn.net/?f=1.2%5Ctimes%2010%5E3ppm)
Explanation : Given,
Partial pressure of water = 0.91 torr
The total pressure of air = 735 torr
Parts per million (ppm) : It is defined as the mass of a solute present in one million
parts by the mass of the solution.
Now we have to calculate the concentration of water vapor in a sample of air.
![\text{Concentration of water vapor}=\frac{\text{Partial pressure of water}}{\text{Total pressure of air}}\times 10^6](https://tex.z-dn.net/?f=%5Ctext%7BConcentration%20of%20water%20vapor%7D%3D%5Cfrac%7B%5Ctext%7BPartial%20pressure%20of%20water%7D%7D%7B%5Ctext%7BTotal%20pressure%20of%20air%7D%7D%5Ctimes%2010%5E6)
Now put all the given values in this formula, we get concentration of water vapor in a sample of air.
![\text{Concentration of water vapor}=\frac{0.91torr}{735torr}\times 10^6=2.1\times 10^3ppm](https://tex.z-dn.net/?f=%5Ctext%7BConcentration%20of%20water%20vapor%7D%3D%5Cfrac%7B0.91torr%7D%7B735torr%7D%5Ctimes%2010%5E6%3D2.1%5Ctimes%2010%5E3ppm)
Therefore, the concentration of water vapor in a sample of air is, ![1.2\times 10^3ppm](https://tex.z-dn.net/?f=1.2%5Ctimes%2010%5E3ppm)