I wonder if/whether she’ll ever reply to my email.
Could you tell me if/whether I’m walking in the right direction to get to the mall?
Do you know if/whether the Ottawa Senators are playing tonight?
But remember when I said that they are not always interchangeable in embedded questions? That’s when “if” expresses a conditional situation where there are no alternatives, and when “whether” expresses a condition where there are at least two alternatives.
I don’t know whether I’ll end up drinking wine tonight.
I can drink wine only if I don’t have to drive.
Confusing right? Sorry, I didn’t make the rules; I’m just explaining them to you.
Another rule with respect to embedded questions is that you can use “or not” after both “if” and “whether” when speaking about alternatives. The difference though is the placement of “or not” in the sentence. We can use “or not” immediately after “whether” or at the end of the sentence/question. With “if”, we can only use “or not” at the end.
I asked whether she wanted to go out for lunch this Friday or not.
I asked whether or not she wanted to go out for lunch this Friday.
I asked if she wanted to go out for lunch this Friday or not.
Here’s another fun rule. A situation in which “if” and “whether” are not interchangeable is when followed by “to”. Only “whether” can be used in this instance.
I didn’t know whether to put on my rain or winter boots.
I had to decide whether to buy the nice, new phone or stick with my ugly, slow one for a bit longer.
I hope this clears things up a little. Feel free to ask questions on this subject or any other at any time.