Question

5. How many grams of KNO3 will be required to prepare 800 mL of 1.40 M KNO3?

Answer 1

How many moles KNO3 will you need? That is M x L = moles KNO3.
Then moles KNO3 = grams KNO3/molar mass KNO3.

Answer 2

113.2