Please Help! a buffer solution is prepared by adding NH4Cl to a solution of NH3. what happens if HCl is added?​

Iknow the answer is a but i don't know why

Will give brainliest it is a lab from k12 here is the linkfor each metal that participated in a chemical change, write the type of metal it is, based on your examination of the periodic table. type your answer here. (score for question 3: of 5 points) were there any metallic compounds that did not react with either the acid or the base? write the type of metal, based on your examination of the periodic table. type your answer here. (score for question 4: of 5 points) make a general statement about the reactivity of the metals in this experiment. type your answer here.

Me i dont know what to do! the table compares the number of electrons in two unknown neutral atoms. comparison of electrons atom number of electrons a 10 d 11 use this information to determine the number of valence electrons in the atoms. which of the following correctly compares the stability of the two atoms? both are unreactive. both are highly reactive. a is unreactive and d is reactive. a is reactive and d is unreactive.