How many moles are in 42.1 grams of NaCl?

0.71

Explanation:

The molecular mass of NaCl is, 23+35.5

= 58.5

1 mole means molecular mass (in gram)

In 58.5 gm NaCl there is 1 mole.

So, 42.1 gm NaCl contains 42.1/58.5 = 0.71 moles.