Answer:
Ag+
Explanation:
If you imagine as if the problem were double replacement, you would pair the Cl with one of the following ions provided in the choices. As seen on Table F, Ag+ paired with Cl- produces an insoluble compound, hence the precipitate. All the other ions shown in the multiple choice section, when paired with Cl- will produce a soluble compound, as a result NOT a precipitate.
This is the thing called the mass number of the thing
Conjugate base of Propanoic acid (
is propanoate where -COOH group gets converted to -CO
. The structure of conjugate base of Propanoic acid is shown in the diagram.
The 
above which 90% of the compound will be in this conjugate base form can be determined using Henderson's equation as propanoic acid is weak acid and it can form buffer solution on reaction with strong base.
= 
+ log![\frac{[Conjugate base]}{[acid]}](https://tex.z-dn.net/?f=%5Cfrac%7B%5BConjugate%20base%5D%7D%7B%5Bacid%5D%7D)
=4.9+log
=5.85
As 90% conjugate base is present, so propanoic acid present 10%.
