Question

What is the number of nitrogen atoms in 12g aluminium nitrate, Al(NO3)3?

Answer 1

The 3 outside means to multiply the inside by that number. AL(NO2)3 has
1 N inside
1 x 3 = 3 nitrogen atoms

The molar mass of Al(NO3)3= 212.996 g/mol
nitrogen is 14 g/mol and is 19.7% if the molar mass
19.7% of 12 g = 2.354g
2.354/14 = 0.196 N