Is else is required in else if statement.

Answer 1

No it is not compulsory to use 'else' after 'if'. But it is compulsory to use 'if' before 'else'.

In one sentence 'if' is compulsory but 'else' is optional

Answer 2

You need not have an "else" after "if", it is just used to do something if at all your "if" fails.

Answer 3

No it's not essentially to have "else" block, bz it's executes only if the given condition is false in "if" block.