pH questions

[infinityandbeyond]

I have trouble with the questions attached. The answers are B and C respectively.

Thanks in advance.

[fun_jirachi]

I dunno if I'm wrong on these ones because I haven't done HSC Chem (is this HSC Chem?), but I'll give it a go

For the first one they all have the same concentration, so you're looking at the pH of the acids. Hydrochloric acid and citric acid are strong and pretty strong, while acetic acid is a weak acid (like its just vinegar right). Since acetic acid is the weakest, it has the highest pH so the answer is B

When you add water to an acid the pH goes up. From what I know I like to think of it as sort of averaging out the pH's but sort of not, so the pH goes up in this question. It rules out B and D. The answer is C because (I'm not too sure about this but uh) I'm pretty sure water dissociates other aqueous stuff into their ions. So I guess that the degree of ionisation goes up because of that because theres more ions, since the OG acetic acid was technically neutral or something

Maybe someone can give you a better explanation, I need to learn this stuff Hope I helped anyway

[infinityandbeyond]

I get it now. I forgot that they asked for the highest pH for the first question. The second one is a little more understandable now. Thanks!

[jazcstuart]

I dunno if I'm wrong on these ones because I haven't done HSC Chem (is this HSC Chem?), but I'll give it a go

For the first one they all have the same concentration, so you're looking at the pH of the acids. Hydrochloric acid and citric acid are strong and pretty strong, while acetic acid is a weak acid (like its just vinegar right). Since acetic acid is the weakest, it has the highest pH so the answer is B

When you add water to an acid the pH goes up. From what I know I like to think of it as sort of averaging out the pH's but sort of not, so the pH goes up in this question. It rules out B and D. The answer is C because (I'm not too sure about this but uh) I'm pretty sure water dissociates other aqueous stuff into their ions. So I guess that the degree of ionisation goes up because of that because theres more ions, since the OG acetic acid was technically neutral or something

Maybe someone can give you a better explanation, I need to learn this stuff Hope I helped anyway

I'll just add onto fun_jirachi's answer 
Just remember that citric acid is still a weak acid, because the definition of a strong acid is that it is fully ionised in water (which citric acid is not). It is slightly stronger that acetic acid though, I think it is because citric acid is a triprotic acid but I'm not 100% sure.

For the second question, remember that pH is a measure of the concentration of hydrogen ions, therefore diluting the solution lowers the concentration of H⁺. This means the solution is less acidic, so its pH has been increased.
Acetic acid is a weak acid so it exists in the equilibrium:
H₂O (l) + CH₃COOH (aq) <---> H₃O⁺ (aq) + CH₃COO^- (aq)
So by adding water you shift the equilibrium to the right, therefore increasing the ionisation.

Hope this makes sense, feel free to ask is you don't understand my explanation 

[infinityandbeyond]

Yep, that makes sense. Thanks!