I read that arrays are contiguous in Virtual Memory but probably not in Physical memory, and I don't get that.
Let's suppose I have an array of size 4KB (one page = one frame size), In virtual memory that array is one page.
In virtual memory every page in translated into one frame so our array is still contiguous...
(In Page Table we translate pages into frames not every byte into its own frame...)
Side Question: (When Answering this please mention clearly it's for the side note):
When allocating array in virtual memory of size one page does it have to be one page or could be split into two contiguous pages in virtual memory (for example bottom half of first one and top half of the second)? In this case at worst the answer above is 2, am I wrong?
Unless the start of the array happens to be aligned to the beginning of a memory page, it can still occupy two pages; it can start near the end of one page and end on the next page. Arrays allocated on the stack will probably not be forced to occupy a single page, because stack frames are simply allocated sequentially in the stack memory, and the array will usually be at the same offset within each stack frame.
The heap memory allocator (malloc()) could try to ensure that arrays that are smaller than a page will be allocated entirely on the same page, but I'm not sure if this is actually how most allocators are implemented. Doing this might increase memory fragmentation.