Answer:
i
b because it says it in the question
The molecular weight is the same as molecular mass. You find this by using the periodic table
The molar mass of Mg(NO3)2 is 148.3
Answer: 2
Explanation:
To calculate the moles :

According to stoichiometry :
1 mole of
are produced by = 4 moles of 
Thus 1.18 moles of
will be produced by=
of 
Mass of 
Thus 85.0 g of
will be required and 2 steps are required to get the answer.