No problem with the asking more questions.
Yes,
whether introduces two or more alternatives into a situation. Here's an example with three alternative choices:
Ex 1:
Whether I tell him at breakfast, at lunch, or at dinner, he'll be happy.
If there is only one alternative presented, the other alternative is the negative of the first.
Ex 2:
Whether I tell him, he'll be happy. =
Whether or not I tell him, he'll be happy. =
Whether I tell him or not, he'll be happy.
In both examples one of the choice is expected (and in this case,
regardless of the choice, he'll be happy.)
If can also introduce two or more alternatives to be considered into a situation. However, it can just as easily introduce only one. The main point is that none of the alternatives is expected to be selected.
Ex 3:
If I tell him at breakfast or at lunch, he'll be happy.
Here the alternatives of
telling him at breakfast and
telling him at lunch are introduced, the result being that when one is chosen
he'll be happy. This statement
also allows for all the possibilities of telling him at some other time or for not telling him at all. And when the conditions under consideration by the
if aren't fulfilled, we don't have any information about what will happen.
Tell me if I'm wrong, but I think you're seeing
Ask him whether he likes peas or corn as structured like this:
Ask him (something) if (the following condition is satisfied).
I can see how it could be viewed that way.
The sense of
if here is very much like
whether. However, the
if means that neither choice is necessarily expected to be taken.
Context might help us:
Ask him whether he likes peas or corn would probably be said when the speaker had peas and corn already cooking on the stove and was about to serve them, or when the speaker was looking at the variety of vegetables he or she could offer as part of a meal and expected one of these choices to be selected. In this case the expected answers are along these lines:
He says he'll take/he'd like peas.
or
He says he'll take/he'd like corn.
or maybe even,
He says he'll take/he'd like both.
Ask him if he likes peas or corn is a more neutral query. The speaker is just asking someone to determine the preferences of another without expecting that either choice will necessarily be selected. There could be many alternatives as answers, such as
I like brussel sprouts,
I don't like either one,
I like both.
However, the speaker is only expressing a desire to know how another views the choices of peas and corn, especially in comparison to each other.
In closing, you'll find people who use
whether and
if interchangeably and situations where they might not be differentiable. If so, it can be hard to determine whether the speaker meant
whether or
if, whether the situation blurs or removes the difference, or whether the speaker is concerned with such hair-splitting at all.
