Answer:
Mass of KNO3= 10g
Molar mass of KNO3 = 101.1032g/mol
Volume = 250ml = 0.25L
No of mole on of KNO3 = mass of KNO3/Molar mass of KNO3
no of mole of KNO3 = 10/101.1032
No of mole of KNO3 = 0.09891
molarity of KNO3 = no of mole of KNO3/Vol (L)
Molarity = 0.09891/0.25 = 0.3956M
Molarity of KNO3 = 0.3956M