plz i need some help in solving some problems in chemistry 101

I want some help in these Question :

1- Calcium nitrate tetrahydrate dissolves in cold water to the extent of 266 g per 100. cm3.
What is the concentration of nitrate ions in this solutio n?
2- 34.62 mL of 0.1510 M NaOH was needed to neutralize 50.0 mL of an H2SO4 solution.
What is the concentration of the original sulfuric acid solution?
3- 35.0 mL of 0.255 M nitric acid is added to 45.0 mL of 0.328 M Mg(NO3)2. What is the
concentration of nitrate ion in the final solution?
4- What mass of K2CO3 is needed to prepare 200. mL of a solution having a potassium ion
concentration of 0.150 M?
5- What is the molar concentration of chloride ions in a solution prepared by mixing 100.
mL of 2.0 M KCl with 50. mL of a 1.5 M CaCl2 solution?
Thank you