[sprentic]

I have a lab exam coming up and I can't figure out how to solve one of the sample problems.

Equal volumes of 1.00 M ammonium nitrate and 2.00 M nitric acid are mixed together. What is the pH of the final solution?
A) one plus the pKa for the ammonium ion
B) one minus the pKa for the ammonium ion
C) zero
D) one minus the pKb for ammonia
E) one plus the pKb for ammonia

This problem is sort of confusing the way the multiple choice answers are listed. Would someone be able to point me in the right direction? Can someone also clarify how "ammonia" and "ammonium ion" are different in the context of this question?

Thanks

[rabolisk]

Ammonium is the conjugate acid of ammonia. What do you know about the pKa of an acid and the pKb of its conjugate base? What is their relationship?