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Compound [A,B,Both Equal] has a faster SN2 reaction due to ["a better leaving group", "a worse leaving group", "more branches at the reacting carbon", "fewer branches at the reacting carbon", "more steric hindrance near the leaving group", "less steric hindrance near the leaving group", "some other reason"]

Comparing Pair 6: Compound [Select] is a better nucleophile due to [ Select]

Answer 1

the halogen reactivity towards the SN2 reaction is as follows

I > Br > Cl > F

here due to size of iodine which is larger and forms readily the positive charge on carbon and here the more will be size and acts as good leaving group

here in aprotic solvents the Br is good leaving group and because of the atomic size

here Compound A is good leaving group or better leaving group more steric hindrance due to the bigger size