Avogadro's number: 6.02 x 10^23 atoms is present in 1mol of a solid (i.e. 22, 400 cm3)
Hence, in 1 cm3, 6.02 x 10^23 /22400 atoms is present = 2 x 10 ^ 19 atoms.
When you ride a vehicle in a fast speed, then your peripheral vision will reduce that is why there is a need for you to follow the direction of the objects when you are travelling in order for you to compensate to the decrease in the field of vision.
Hubble noticed that the galaxies were moving away from us, which meant the universe was expanding.
This is why constellations change over time. In some years, the Big Dipper won't actually look like a dipper anymore.
Current= voltage divided by resistance
120/30=4