Question

What is the number of moles in 4.00 g of magnesium oxide,MgO?

Answer 1

Answer: 0.1 mole MgO

Explanation: 1 mole of MgO is equal to its molar mass.

4.00 MgO x 1 mole MgO/ 40g MgO

= 0.1 mole MgO

Answer 2

moles= mass/rfm
MgO 16+24=40
4/40
moles= 0.1