I need help with this chemistry assignment!!

In which layer of earth do most earthauakes occur a_ inner core b_outer core c_mantle d_crust

If a solution is considered basic, then a) the hydroxide ion and hydronium ion concentrations are equal. b) the hydroxide ion concentration is less than the hydronium ion concentration. c) the hydronium ion concentration is greater than the hydroxide ion concentration. d) the hydroxide ion concentration is greater than the hydronium ion concentration.

Analyze how limestone is weathered and identify the features that are formed as a result of this dissolution