Question

products formed during addition of hbr with 3-methylbut-1-ene

Answer 1

When 3-methylbut-1-ene is reacted with HBr , then One major and One minor will be formed.
Here the formation of Markovinikov's products occurs with cation and second carbon atoms.

Reactions :- Refer to the attachment for clear reaction :-
  ___________________________
                                                
3-Methylbut-1-ene  +HBr ------→ 2-bromo-2-methylbutane + 2-bromo-3-methylbutane 
____________________________

Explanation :- 
(i) Here 2-bromo-2-methylbutane is the major product & 2-bromo-3-methylbutane is the minor product.
(ii) Bromine will attack there in formation of2-bromo-2-methylbutane

Hope it Helps :-)