I have questions about future real conditional and future unreal conditional

Question

There are a couple of sentences that I usually get mixed up.

1. If you try to take pictures of restricted exhibitions, a member of the staff will ask you to put your camera away.
2. If you are caught with food or drink inside the museum, you will be asked to dispose of it immediately.
3. If a person eats healthy foods like fruits and vegetables, It is more likely that they will be healthy.
4. It would be great if you could learn something every time you went to a museum.

I understand future real conditional and future unreal conditional like followings.

Future real conditional can be used in a situation where something is more likely to happen.

Future unreal conditional can be used when I'd just like to imagine and guess what it would be like if something happened or in a situation where something is impossible to happen.

And important thing is that it seems like I can use either of them in some situation because Future unreal conditional can also be used in imaginary situation.

1. If you tried to take pictures of restricted exhibitions, a member of the staff would ask you to put your camera away.
2. If you were caught with food or drink inside the museum, you would be asked to dispose of it immediately.
3. If a person ate healthy foods like fruits and vegetables, It would be more likely that they would be healthy.
4. It will be great if you can learn something every time you go to a museum.

So, can I use both of them in these 3 sentences?

Answer 1

Instead of future real / unreal conditions let's put it this way

Future likely / unlikely conditions.

When the condition is likely you use the verb in the infinitive form

For example

1. If you try to take pictures of restricted exhibitions, a member of the staff will ask you to put your camera away. (Here you think that the person whom you are telling this is likely to take pictures in the exhibition)

Now suppose you are addressing the same sentence to a group of people (where they are unlikely to take pictures inside the exhibition) then you use verb in the past tense i.e.

2. If you tried to take pictures of restricted exhibitions, a member of the staff would ask you to put your camera away. (It means I don't think you will try to take pictures)

Let's see few more examples

1. If he asks me, I will tell him. (I think he will ask me)
2. If he asked me, I would tell him. (I don't think he will ask me)

So using the verb in its infinitive form or in the past tense causes the meaning of the sentence to differ a bit.

Let's see your last sentence and the thinking that goes inside when you use 'will' or 'would' in the condition.

As we know 'would' is the past tense of 'will'. So the verb used in the past tense denotes less possibility of something happening. So when you say

1. It would be great if you could learn something every time you went to a museum. (It means you don't think the person will try to learn everytime he visits the museum)

But when you say

2. It will be great if you can learn something every time you go to a museum. (It means you think that he might try to learn everytime he he visits the museum.)

Let's take TRomano's example

1. It will be great if you can stop by and say hello when you arrive on campus. (It means i think you will come)
2. It'd be great if you can stop by and say hello when you arrive on campus. (I don't think you'd come)

Answer 2

The only sentence in your second set that gives me any pause is #4. The rest are fine, to my AmE ear.

It will be great if you can learn something every time you go to a museum

In the following sentence, I think the same tenses work OK:

It will be great if you can stop by and say hello when you arrive on campus.

The difference between the two has to do with the temporal aspect. In your sentence, we have every time and in mine we have when. Other native speakers may disagree with me, but I find that "will be" and "can" don't work very well with the sort of open-ended wishful thinking expressed in your sentence; they work much better with a finite, specific time.

P.S. But if we imagine a new technology in the future, where museum-goers plug a USB cable into a port behind their left ear, and download information directly into their brains, we might say:

It will be great when you can learn something whenever you go to a museum.

There, it works, but note that "great if" becomes "great when".