Question

The sun is visible to us 2 minutes before the actual sunrise and two minutes after the sunset give reason 0

Answer 1

It's all about refraction.Not only we observe advanced sunrise but also delayed sunset.This is because when light enters from vacuum to earth's atmosphere,it basically enters from rarer to denser medium and bends towards horizon.During sunrise, when the sun is just below the horizon, our atmosphere causes the light rays to bend and we see the sun early. Similarly, at sunset, the apparent position of the sun is visible to us and not the actual position due to the same bending of light rays effect.