So,
The first thing we need to remember is the molarity definition.
Molarity is a concentration unit which is a relation of the solute moles of a substance and the volume of the solution in liters. Writing this as an equation, we got that:
In this question, solute is CuNO3. First, we need to find the number of moles of CuNO3, since we're given 6.26 grams and not moles. To find the moles, we divide the amount in grams by the molar mass of CuNO3:
Now, given that the molarity of the solution is 0.820M, we could replace the values in the equation so we could solve for the volume V:
We're asked to find the volume in mL, so we multiply by 1000:
Therefore, the answer is 60.8mL