4.6g of sodium is reacted with excess of water. Calculate the volume of hydrogen evolved at NTP?

First you look at your periodic table to get the molecular mass of sodium. You do have a periodic chart, right? You need one. That is 22.989768 grams per mole. 4.6/22.989768 = 0.2 mole.

Now you write the formula: 2Na + 2H2O --> 2NaOH + O2 This says 2 moles of sodium will produce 1 mole of oxygen, so 0.2 mole will produce 0.1 mole.

The rule of thumb is that 1 mole of any gas occupies 22.4 liters at STP so your answer is 2.24 liters.

This is simple arithmetic. You need to be perfectly prepared in arithmetic to do well in chemistry. Perhaps you should consider dropping the class and taking a refresher course.