At standard temperature and pressure, one mole of gas occupies 22.4 L. Knowing this, we must convert the grams to moles and moles to liters to get your answer. Here's how you do it!
[tex]\frac{5.8gH2}{1} | \frac{1moleH2}{2.0gH2}| \frac{22.4LH2}{1moleH2} \\ \frac{5.8*1*22.4LH2}{2.0} \\ \frac{129.92LH2}{2.0} \\ 64.96LH2 \\ 65LH2 [/tex]
With significant figures accounted for, 5.8 grams of hydrogen gas occupies 65 L.
Hope this helps!