Which of the following fluro-compounds is most likely to behave as a Lewis base ?

MY and NY₃, two nearly insoluble salts, have the same K_sp values of 6.2 $$ \times $$ 10^$$-$$13 at room temperature. Which statement would be true in regard to MY and NY₃?

Which one of the following pairs of solution is not an acidic buffer ?

What is the pH of the resulting solution when equal volumes of 0.1 M NaOH and 0.01 M HCl are mixed?