The number of moles of solute in 250 ml of a 0.8M solution is 0.2 moles
calculation
by use of the formula of finding molarity
molarity =moles/volume in liters
molarity = 0.8 M
moles =?
volume =250 ml = 250/1000 = 0.25 L
by making moles the subject of the formula
moles = molarity x volume
= 0.8 x0.25 = 0.2 moles