2NO(g) + O2(g) ==> 2NO2(g) ... balanced equation
From this balanced equation we see that 2 moles NO reacts with 1 mole O2. At constant pressure and temperature, we can also say that 2 liters of NO reacts with 1 liter of O2. Then we can determine volume of O2 needed to react with 4.8 L of NO as follows:
4.8 L NO x 1 L O2 / 2 L NO = 2.4 L of O2 required