Step-by-step explanation:
It is known that number of moles equal mass divided by molar mass of compound.
Mathematically, Number of moles =

Since, it is given that mass is 15.6 g and molar mass of NaCl is 58.44 g/mol.
Therefore, calculate the number of moles of NaCl as follows.
Number of moles =
=
= 0.266 mol
Thus, we can conclude that there are 0.266 moles of NaCl are equivalent to 15.6g NaCl.