Ok I can't really say for sure if the blast radius will touch or overlap the stack if I look at the picture,it might just be within the radius, experienced players might assist.
Not sure how many nukes you have to spare maybe try it.The other option is to be active and wait until the stack split or moves then hit the center when the stack will be within radius.

I've never tried this but I think yes. The splash radius should be 50 (if I remember correctly), which is the same as the range of regular artillery. It's enough to select an artillery, try a Move prompt to the target province and a circle will appear around, showing the range of 50.

But I'm aware that this is 8 days later, so: did it work? Also, were you using a nuclear rocket or just a nuclear bomber? The rocket can't get shot down at all, so it could be fired directly at anything and still do damage.

yes if nuke a province next door to a stack, that stack will get hit if within blast radius, approx. 1k hp damage i've found and won't be shot down. now makes me wonder why i so rarely take the time to research that , oh yeah time and resources involved can be a pain

Nukes are kindof situational yes. You need a big enemy army to hit, and even then you paid like 10k manpower to do 1k damage. For that, you could produce like 600hp worth of units and bring that enemy stack down to 400hp with them. So the difference between making or not making a nuke was just that 400hp. With this small a gain, it will take long to pay off, given how much you've invested researching it

Thats why i never used nukes. But I might at some point. I'm sure they'll be quite useful in some situations

How to use Nuclear Bombers