Is this in correct grammar?


If I were you, I would ask whoever is in charge for their opinion.

Yes

First of all, look at your spelling. Spelling is part of grammar too.

It's grammar, not grammar.

Now, the sentence is not correct. There is one word you can and should change.

The word "whoever," should be something else. What do you think it should be?

Your sentence:
If I were you, I would ask whoever is in charge for their opinion.

I would change it to:

If I were you, I would ask who's ever in charge for their opinion.

Their should also become something else. You are talking about a singular object.