calculate the number of moles in 1.20 x 10 23 molecules of potassium hydroxide

Answer 1

You should have learned about Avogadro's number. Avogadro's number is number of atoms or molecules (or other things) in one mole of a substance. It is defined as 6.02214 × 10²³ molecules (or other things) per 1 mole. To determine the number of moles take the number of molecules and divide by Avagadro's number so (1.20 x 10²³)/(6.02214 × 10²³) = 0.19926

But since there are three significant figures in the original given unit, we round to 0.199 moles

1.20 x 10 23 molecules of potassium hydroxide = 0.199 moles of potassium hydroxide