Solubility question

please answer all parts in correct sig figs

a) write the equation that relates calcite solubility (Ca²⁺) to the partial pressure of CO₂

b) calculate the concentrations (in mmol/L) of dissolved calcium in equilibrium with calcite at 25C for the three following log10 partial pressures of CO2 (-3.57 1st pre industry atmosphere, -3.39nd current atmosphere and -1.51rd soil atmosphere) Assume activity = concentration for these calculations

c) what do the three results tell us about the CO2-calcite equilibrium-Ca concentration in relation to the atmosphere and their attributed activities?