Answer:
b. 1.20x10^24 molecules NH3
Explanation:
At STP, one mole of gas has a volume of 22.4 dm^3
1 dm^3 = 1 L
Therefore,
44.8 L = 44.8 dm^3
This means that there are 2 moles of NH3 in 44.8 L at STP.
number of molecules = number of moles times avogadro's number
Avogadro's number = 6.02x10^23
Numner of molecules = 2 x 6.02x10^23
= 1.204x10^23 molecules