Why is it important to have a balance of gases in the atmosphere?

The greenhouse gases absorb some of this energy and radiate much of it back towards the surface whilst the rest is radiated out to space. This plays an important role in keeping the Earth's surface warm and able to sustain life.

The answer is 4f======since electrostatic force is given by    we let f be the electrostatic force when  r = 1 m    if we let  denote the electrostatic force when the distance is decreased so that r = 0.5m, then    we established earlier that f = kq₁q₂. therefore    the force will now be 4f.

None. nothing. zero. zilch.