if u add if you add 2.0 ml of 10.0 M HCl to 500 ml of a .10 M NH3, what is the pH of the resulting solution? for NH3, kb=1.8X10^-5

NH3 + HCl ==> NH4Cl

moles NH3 = M x L = ??
moles HCl = M x L = ??
Determine from the moles you have which reagent is in excess, determine the molarity from M = mole/L and find pH of the resulting solution. I suspect NH3 is in excess and that will produce a buffered solution. If you have been taught the Henderson-Hasselbalch equation, use that to determine the final pH of the solution. If not, post back with your work or use
Ka expression to solve for pH.