1. Find the molar mass of sodium hydroxide (NaOH):

* Na (sodium): 22.99 g/mol

* O (oxygen): 16.00 g/mol

* H (hydrogen): 1.01 g/mol

Total molar mass of NaOH = 22.99 + 16.00 + 1.01 = 40.00 g/mol

2. Use the molar mass to convert grams to moles:

* moles = mass / molar mass

* moles = 40 g / 40.00 g/mol

* moles = 1 mol

Therefore, there is 1 mole of sodium hydroxide (NaOH) in 40 grams of sodium hydroxide.