(A) The ionic product of water at 100∘C is 51.3×10−14. So, this statement is incorrect. (B) On increasing the temperature, pH of solution also decreases. (C) Since, Na2HPO4 is a salt of strong base NaOH and weak acid H3PO4, it gives a basic solution on hydrolysis. (D) NH3 can act as both Bronsted acid and base because it can accept H+ion to form NH4+and donate H+ion to form NH2−. Hence statements B, C, D are correct.