How many moles of sodium hydroxide are found in 120 grams of Na OH?

The mole of a metal, such as sodium, is generally assumed to consist of Avogadro's Number of single atoms. The gram Atomic Mass of sodium is 22.9898. The number of moles in 120 grams of Na is therefore 120/22.9898, or 5.22, rounded to the justified number of significant digits.