Question

Describe how you would make a 125 mL of 0.025 M solution of potassium dichromate?

Answer 1

How many mols do you want? That's mols = M x L = approx 0.003 but that's just an estimate.

Then grams = mols x molar mass = approx 0.9 g

So you weigh out the amount of K2Cr2O7 you want, add to a 250 mL volumetric flask, add some water, swirl to dissolve, then add to the mark with DI water. Mix thoroughly and label.