Indentify the conjugate acid base pair for the following reaction in aqueous solution
i) HS^- (aq) + HF \(\rightleftharpoons \) F^-(aq) + H₂S(aq)
ii) HPO^2-₄ + SO₃^2- \(\rightleftharpoons \) PO₄^3- + HSO₃^-
iii) NH₄⁺ + CO₃^2-  \(\rightleftharpoons \) NH₃ + HCO₃^-

Account for the acidic nature of HClO₄ in terms of Bronsted – Lowry theory, identify its conjugate base.

When aqueous ammonia is added to CuSO₄ solution, the solution turns deep blue due to the formation of tetra ammine copper (II) complex,\({ [Cu({ H }_{ 2 }O)_4] }_{ (aq) }^{ 2+ }+ 4{ NH }_{ 3 }(aq)\rightleftharpoons { [Cu{ ({ NH }_{ 3 }) }_{ 4 }] }_{ (aq) }^{ 2+ }\) among H₂O and NH₃ Which is stronger Lewis base.

The concentration of hydroxide ion in a water sample is found to be 2.5 × 10^-6M. Identify the nature of the solution.

A lab assistant prepared a solution by adding a calculated quantity of HCl gas 25⁰C to get a solution with [H₃O⁺] = 4\(\times\)10^-5M. Is the solution neutral (or) acidic (or) basic.