If v Whether

[stevefeiner5]

Can anyone explain when one would use if and when one would use whether?

[ps63739]

We use if for conditions, like I will do it, if I can.

Whether is when there are two outcomes of the questions.

I will go Church, wheather it rains. (Or not hidden).

You have to make sure usage doesn't change the meaning.

Like for the sentence if you use 'if' will change the meaning.

I will go to church if it rains. (if rains I will go to church).

Refer to manhattan GMAT Grammar book. They have explained pretty good.