1.  Express 95 mg/l of Ca²⁺ as milligrams per liter of CaCO₃.

2.  Express 221 mg/l of Ca(HCO₃)₂ as equivalents per liter of CaCO₃.

3.  Determine the concentration of the following ions at equilibrium with the solid at 25 degrees C. 

a.  Cr³⁺ + 3OH- >>>Cr(OH)₃, K_sp  = 6 x 10^-31 

b.  CA²⁺  + 2 OH^- >>>Ca(OH)₂,   Ksp = 8 x 10 ^-6

4.  A 100-ml sample of water is titrated with 0.02 N H₂SO₄. The initial pH is 9.5 and 6.2 ml of acid is required to reach the pH 8.3 endpoint. An additional 9.8 ml of the acid is required to bring the sample to the pH 4.5 endpoint. Identify the species of alkalinity present and determine the concentration (mg/l) of each expressed as mg/L as CaCO₃.