Help me with two questions in the attachment please :)

Question

anonymous · Answer

attachment

aaronq · Answer

what part is giving you problems?

anonymous · Answer

I cannot figure out how B is correct because wouldn't only Br be replaced with CN ? And after nitril hydrolysis CN changes to CO2H to give carboxylic acid i'm talking about 28

aaronq · Answer

in fact, CH2Br would be replaced with CO2H

anonymous · Answer

What how? Can you write equation for it plzzzz?

anonymous · Answer

I figured out question 29.

aaronq · Answer

Sorry i had a phone call. Look at the mechanism i attached

anonymous · Answer

28 ans is B?

anonymous · Answer

This is so confusing :/ what i learned was the reaction between KCN and halogenoalkane and its a nucleophilic reaction halogen is replaced with CN and nitril is hyrolysed so CN gets replaced with CO2H

anonymous · Answer

Yeah @HamidAliAbbasi but do you know the reaction?

aaronq · Answer

"CN gets replaced with CO2H " this is right

aaronq · Answer

sorry, i think im contradicting myself and maybe was wrong initially

aaronq · Answer

yeah B is right

anonymous · Answer

I just checked the markscheme to confirm it's written there B is the correct answer for 28

anonymous · Answer

Oh yeah yeah

anonymous · Answer

But how B is correct that's the problem

aaronq · Answer

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