In this question, we have to calculate the number of moles of NaOH based on the given mass, 20 grams, and its molar mass, 39.997g/mol, in order to do that, we can do the following calculation:
39.997g = 1 mol of NaOH
20g = x moles of NaOH
39.997x = 20
x = 20/39.997
x = 0.500 moles of NaOH in 20 grams of it
