It's B. Since density equals mass/volume. The missing quantity needed is mass.Hope this helps.
Matter is the correct word.
The mass of gas in the tank has been 222 g. Thus, option B is correct.
The volume occupied by 1 mole of gas at standard temperature and pressure has been 22.4 L.
<h3>Computation for the Mass of gas</h3>
The volume of gas in the tank has been given as 170 L.
The moles of gas in the tank has been:
![\rm 22.4\;L=1\;mol\\\\ 170\;L=\dfrac{1}{22.4}\;\times\;170\;mol\\\\ 170\;L=7.58\;mol](https://tex.z-dn.net/?f=%5Crm%2022.4%5C%3BL%3D1%5C%3Bmol%5C%5C%5C%5C%0A170%5C%3BL%3D%5Cdfrac%7B1%7D%7B22.4%7D%5C%3B%5Ctimes%5C%3B170%5C%3Bmol%5C%5C%5C%5C%0A%20170%5C%3BL%3D7.58%5C%3Bmol)
The moles of gas in the tank has been 7.58 mol.
The molar mass of the gas has been 32.0 g/mol.
The mass of gas has been calculated as:
![\rm Mass=Moles\;\times\;Molar\;mass\\ Mass=7.58\;\times\;32\;g\\ Mass=242\;g\\ Mass\approx 222\;g](https://tex.z-dn.net/?f=%5Crm%20Mass%3DMoles%5C%3B%5Ctimes%5C%3BMolar%5C%3Bmass%5C%5C%0AMass%3D7.58%5C%3B%5Ctimes%5C%3B32%5C%3Bg%5C%5C%0AMass%3D242%5C%3Bg%5C%5C%0AMass%5Capprox%20222%5C%3Bg)
Thus, the mass of gas in the tank has been 222 g. Thus, option B is correct.
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