Answer:
 58.5g/mol
Step-by-step explanation:
Given substance: 
 Sodium chloride = NaCl 
 Unknown: 
Molecular mass = ? 
Solution: 
The molecular mass of a compound is the gram-formula mass or gram-molecular weight of the compound. 
It is determined by adding its component atomic masses and then express in grams per mole; 
Atomic mass of Na = 23g
Atomic mass of Cl = 35.5g 
 NaCl = 23 + 35.5 = 58.5g/mol