No. Not at all, I don't think.
Because rats are WAY bigger than mice (unless its like, a super small rat)
and even then, the rat would probably kill the mouse. I don't recommend it.
A rat could eat a snake.
Not for long. Rodents grow quickly and the rat will eventually eat the mouse.
In some cases it is possible
Not before the rat eats the mouse.
no because rats and cats are enemies the cat will eat the rat
You can buy mouse and rat food at the pet shop. Rodents also like to eat fruit, vegies, seeds and bread. Your options are endless :P
a mouse
The rat will more than likely kill and eat it. Rats are predatory species, and will prey on smaller rodents.
A rat is a rodent and it is bigger than a mouse. However the largest rodent is a capybara and that is the size of a pig.
You should not keep a rat and a mouse on the same cage together, The rat will most likely kill the mouse as that is their natural instinct.
Mouse House or Rat flat
giant rat