For example i have this exercise that something like that will be on my exam, i just want to understand it, from where and how to begin ranking idk why but it seems so hard to me 

Acid group COOH high acidic, followed by ketogroups, ester and alcohol

2 minutes ago, chenbeier said:

Acid group COOH high acidic, followed by ketogroups, ester and alcohol

im a beginner on organic chemistry, can you tell me which of these are the ketogroups and ester groups?

R-CO-R' Keto, RCOOR' Ester

But I suggestion to get a book of organic chemistry or use the WEB. Acidic will be the H close to them.

The CH2 between the two Keto groups in c will be acidic

Edited January 4, 20241 yr by chenbeier

7 minutes ago, chenbeier said:

R-CO-R' Keto, RCOOR' Ester

But I suggestions to get a book of organic chemistry or use the WEB.

ok and which is more acidic B OR C ?

Edited January 4, 20241 yr by Henri_1234

C is more acidic, why is it so. Check - I and / or - M Effect.

1 hour ago, Henri_1234 said:

ok and which is more acidic B OR C ?

The groups which tend to be the most electron-withdrawing will make it easier for H+ to be released ( more stable anion).  A carbonyl C=O can spend some time as C⁺-O⁻. So the CH2 between 2 carbonyls gets the effect from both sides, making it easier for one of the Hs to come off, leaving an enolate anion, cf. keto-enol tautomerism: https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Organic_Chemistry_(Morsch_et_al.)/22%3A_Carbonyl_Alpha-Substitution_Reactions/22.01%3A_Keto-Enol_Tautomerism. 

You can apply the same logic to A vs. F.

If you have an exam coming, you must have some revision notes or lecture material on this kind of thing. 

Edited January 4, 20241 yr by exchemist