At STP, what is the volume of 46.8 grams of ammonia gas, NH3?

I dont think you can do grams to volume, so first you have to convert 46.8g to moles by multiplying it by the molar mass of ammonia (NH3) example:

46.8g x 1 mol NH3/17.031 g NH3 = 2.75 mol

the grams cancel out leaving you with mol as the unit. Then you can convert with STP, example:

2.75 mol x 22.4L/1 mol = 61.6L

The mols cancel out so your left with liters as the unit. I hope this helps i’m not too good with chemistry but this is what i assumed you had to do

i think   the answer is c hope i'm right