What is the [H+] concentration of a solution whose pOH is 12.40?

Which statement is true about ionic compounds?

What is the mass defect of a mole of nuclei with 1.8 x 10^15 j/mol binding energy?

The characteristics of two different types of reactions are shown below: reaction a: electrons are gained by the atoms of an element. reaction b: protons are lost by the atom of an element. which statement is true about the atoms of the elements that participate in the two reactions? their identity changes in both reaction a and reaction b. their identity changes in reaction a but not in reaction b. their identity changes in reaction b but not in reaction a. their identity remains the same in both reaction a and reaction b.