How does the electric force between two charged particles change if the distance between them is increased by a factor of 2

What is the earliest point in the universe that we can observe? why can’t we see back further than this?

In a stagnant pool of water, a crayfish may spend much of its time lying with one side of its carapace near the surface of the water. in this position, it will move the walking legs on that side in a rhythmic back-and-forth motion. explain the likely function of this behavior.

The least penetrating form of radiation is