Which of the following is a conjugate acid-base pair

Question

Which of the following is a conjugate acid-base pair?

a)NaF and F^-

b)None of these

c)NH2^- and NH4^+

d)H2O and O2-

e)All of these

Answer 1

Do any of them differ by a single H atom? No. Therefore the correct answer is (b) None of these.