For a reaction to be spontaneous at all temperatures, the values of enthalpy change and entropy change should be

Find $\Delta n$ when 1 mol of each $\text{NH}_{3(g)}$ and $\text{HCl}_{(g)}$, reacts to form solid $\text{NH}_4\text{Cl}$.

What is the solubility product of binary sparingly soluble salt BA if 100 mL saturated solution of salt consist $10^{-4}$ moles at room temperature?

Calculate pOH of 0.001M HCl solution.