How many grams of solid K2CO3 are needed to prepare 150.mL of a 0.50% by volume K2CO3 solution

Also if you can help me with two more.

2) How many grams of solid KOH are needed to prepare 100. mL of a 1.7 M solution?
3) How many mL of a 10.0% by volume stock solution of HCI must be diluted with enough water to make 300. mL of a 1.5% by volume solution?

this must be w/v
0.5% w/v in 150ml means that there would be 0.5g K2CO3 in 100ml solution. assuming that the density of the soultion = 1g/ml, we have 150g solution
0.5% of 150g = 0.75g K2CO3

1.7M x 0.1L = 0.17moles KOH required
0.17moles KOH x 56.1g/mole = 9.54g KOH

10% v/v HCl
10ml of 100ml = HCl, 90ml = water
%1 x v1 = %2 x v2
10% x ?L = 1.5% x 0.3L
0.045L or 45ml of the 10% HCl solution in 255ml water