According to the Avogadro's law, equal volumes of all gases contain equal number of moles under the same conditions of temperature and pressure.
Here the initial volume, [tex] V_{1} = 120.0 mL [/tex]
Initial moles of the gas, [tex] n_{1}=2.38 mol [/tex]
Final volume of the gas [tex] V_{2} = ? [/tex]
Final moles of the gas [tex] n_{2}= 1.97 mol [/tex]
Plugging in the Avogadro's equation,
[tex] \frac{V_{1}}{n_{1}} = \frac{V_{2}}{n_{2}} [/tex]
[tex] \frac{120.0 mL}{2.38 mol} = \frac{V_{2}}{1.97 mol} [/tex]
[tex] V_{2} = 99.33 mL [/tex]
Therefore the 1.97 mol of the gas occupies 99.33 mL at constant temperature and pressure.
