Final answer:
If the Sun became a black hole, Earth's orbital period would remain the same because gravitational pull depends on mass and distance, not size or state of the celestial body.
Step-by-step explanation:
If the Sun were to collapse to form a black hole, Earth's revolution period around the Sun (now a black hole) would not differ from what it is now. This is because the gravitational pull of an object is determined by its mass and the distance to it, not its size or state. So, if the Sun were to become a black hole without losing any mass in the process, Earth's orbit would remain unchanged. According to Kepler's third law, the orbital period of a planet is related to its distance from the central body and the mass of that body.
When a very massive star collapses at the end of its life, if no known force can support against its own weight and the remaining mass is more than three times that of the Sun, it may become a black hole. However, the Sun is expected to become a red giant and may end its life as a white dwarf, which is a much different process than collapsing into a black hole.