How many molecules of ammonia, nh3, are in 3 moles of nh3?
51.12 molecules
4.98 x 10^-24 molecules
307 molecules
1.81 x 10^24 molecules

The number of molecules in one mole of any substance is equal to Avagadro's number

Avagadro's number is 6.023 X 10²³

Thus

1 mole = 6.023 X 10²³ molecules

for ammonia we are provided with three moles

so to obtain the total number of molecules of ammonia in three moles we will multiply the Avagadro's number with three

total molecules = 3 X 6.023 X 10²³

Total molecules of ammonia = 18.069 X 10²³

In scientific notation

Total molecules of ammonia = 1.8069 X 10²⁴ = 1.81 X 10²⁴