carbocation rearrangement
We already know stability order of carbocations due to hyperconjugation, Resonance and induction
30 >20> 10
Now if a carbocation is less stable means 10 then it can undergo rearrangement by shifting a H or CH3 from adjacent carbon to form more stable 20 or 30
This is called as hydride shift or methyl shift
Hydride shift is more favorable due to less bulky nature of H then methyl group.
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