Easy one

preferably SN2/E2. Dominant among them will be E2

Yeah even I think it should be E2 / SN2 .

But ans given is E1 / SN1

But it should be SN2 / E2 only. Here E2 will be dominant coz the substrate is very hindered and substitution is not feasible. The base is strong, therefore E2 > E1. SN1 is not possible at all.

First of all the alpha carbon is primary. Hence we check bimolecular mechanisms first, S_N2/E2. Supporting this is the strong and unhindered base.
But the beta carbon is bulky, being tertiary, S_N2 is ruled out. E2 should be the dominant mode of attack. Should. What we then see is that we have no beta-hydrogens. We can't facilitate an E2 reaction without those.
Slip down to E1/S_N1. Once the bromine atom leaves, the carbocation rearranges to form a tertiary one, and then the base being unhindered attacks. The final preferred mode will be S_N1.

oh yeah, Correct.. didn't thought of trying this by writing it down. E2 is ruled out correct... But pritish, how will you compete E1 / SN1 in this?? By temperature? E1 holds the possibility too..

Thanx a lot pritish

yeah ... got that.. It will be SN1 only.. not E1.. correct.. right.

Arey yaar I forgot to add one line : E1 is also possible if hydroxide ion abstracts a hydrogen..lol

now.. no.. nahi yaar.. E1 will not be possible.. considering OH- as strong base will not yield us E1 product, so in this question, we will consider nucleophilic character of OH- and that's the reason, it is used in SN1 innit.. including the fact that we have eliminated possibility of E2 / SN 2. SN1 holds more chances than E1 because of OH- weaker nucleophiclic char as compared to basic character .
What you say?? haa

Substitution = Stable nucleophile/Delocalised charge
Elimination = Localised charge/Strong base
Hydroxide ion is a strong base...

see gyz , u r already confirmed this reaction 2 undergo SN₁ / E₁ pathway. then hw com u r discussing abt the nucleophile's strength ?

u must be knowing that the Rate determining step involved here is dissossiation of alkyl halide frm substrate. thus , this pathway is independent of reactivity, strength and concentration of the nucleophile.

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