The nitric acid was purchased as a solution that has 70% HNO3. That volume (mL) of this solution is necessary for preparing 250 mL

Question

Solution 2.0 mol L-1? The density of HNO3 (aq) 70% is 1.42 g cm-3

Answer 1

What is the molarity of the initial HNO3? That's
1000 cc x 1.42 g/cc x 0.70 x (1/63) = approx 16 M but you need to do that more accurately.
Then mL1 x M1 = mL2 x M2
mL1 x 16 = mL2 x 3.0
mL1 = ? = mL of the initial 70% solution.