To determine the number of moles of solute in a solution, we need to use the formula:
moles of solute = concentration (in M) x volume (in liters)
However, before we can use this formula, we need to convert the volume from milliliters (mL) to liters (L):
80 mL = 80/1000 L = 0.08 L
Now we can use the formula to find the number of moles of solute:
moles of solute = concentration x volume
= 0.35 M x 0.08 L
= 0.028 moles
Therefore, there are 0.028 moles of solute in 80 mL of a 0.35 M solution.