According to me b is more acidic so less pka value.. kindly check

it has the lowest pka value

As it is most acidic

So more the acidity lesser is the pka

I hope you got this

please ask if you don't get

I was asking when to check for annelation effect bcoz these are showing annelation effect c and d. still more acidic

Annelation effect is sharing of resonance. So completely resonance vs sharing of resonance is compared.

Here aromaticity is in pictures

a & b don't get aromaticity character

it is planar molecule due to restricted rotation of benzene rings. and have maximum resonance

comp. B also have planar shaped but less resonance than D

comp. A and C are non planar due to bulky rings

so resonance is not possible in A and C.

compound A is found in propeller shape

check it

got it?

hope this will help you 🙏🙏

annelation effect is taking place in D na

yes, but we will compair with other aromatic compounds also but you can see that other compounds given here are non planar (except B, it is non aromatic)

so annelation effect us not dominant here. here we will check only resonance. D is planar having maximum resonance

sir then when to check annelation?

when other compounds also sho annelation effect. so we can compair between them

if one molecule is showing annelation effect and other is not showing, then we will make non annelation one more acidic na?

no, we will check other factors just like this question

among C and D which one more acidic and why?

D is more acidic because C is non planar so due to lack of resonance it is less stable so less acidic than D which is planar and have resonance

After deprotonation carabnion is formed which in the case of option D is more resonance stabilosed ...so most acidic

For option B it is in resonance with only two benzene ring and carbanion is not as much stabilised as like other compound in diff options

So option D is correct

sir but annnelation effect is taking place at D na?