You need to make an aqueous solution of 0.202 M which equal to 0.202 mol/liter. If you only have 125ml solute, then the amount of calcium bromide needed would be:
concentration = mass / volume
0.202 mol/ 1000ml= mass / 125ml
weight= (0.202 mol/ 1000ml) * 125ml= 0.02525 mol
If you need to convert the mass into g it would be: 0.02525 mol* 200g/mol= 5.05 grams
