Hi, there. I'm happy to give my 2 cents here.
First of all, the big train-wreck grammar mistake in these situations would be to use "if" instead of "whether". That's the BIG rule, and you already seem clear on that.
Sentences #2 & #3 are grammatically suspect --- not outright wrong, but technically they are redundant. If I say --- "I am not sure whether I would be going to office" --- that already implies a choice, an uncertainty --- it already implies that I may or may not go to the office. Therefore, adding the words "or not" don't really add any new meaning to the sentence --- they are redundant. I am not sure I have ever seen GMAT SC get so picayune as to test on that subtlety, but it's good to keep in mind.
The first sentence is an interesting, and rare, case --- presenting a second alternative that is not merely "not" + the first alternative.
I am not sure whether I would be going to office or would be taking a leave.
This is perfectly correct.
Incidentally, I want to caution you -- all three of these have involve the
subjunctive, which only would be appropriate if this sentence were part of some hypothetical scenario.
In other words, if the primary decision is simply about going to work, a decision wholly self-contained and not dependent on any other uncertain/unknown external factor, then I would say:
I am not sure whether
I am going to work right now. . . . or . .
I am not sure whether
I will go to work tomorrow
The subjunctive would be appropriate only there is some larger uncertain/unknown external factor at play. That could be --- my wife goes into labor, a 9.0 earthquake strikes, the power goes out, the Apocalypse commences, or the Cubs win the World Series --- if any one of those were to happen tomorrow, then I am not sure whether I
would go to work.
Also, we wouldn't have to use the present progressive "would be going", unless we needed to emphasize that something else were simultaneous with my action of going to work.
Does all that make sense? Let me know if you have any questions at all about this.
Mike
