Why are there four fundamental forces? How ere they deduced?

The four fundamental forces of the universe are understood to be electromagnetism, gravity, the strong and weak nuclear forces; it is likely that there was only one unified fundamental force during the Big Bang, but as the universe cooled, the four forces we know of today were produced from this unified force. This is really physics, not chemistry.

With varying degrees of success over the years, physicists have spent many years attempting to determine the relationship between the forces, but much remains to be discovered.

I don't think anyone knows why there are four forces; the same is true for why the speed of light has a given value or why the charge on an electron has a given value. These factors seem to have been set at the time of the big bang, and there might be other universes with different circumstances and different numbers or quantities of fundamental forces.

A physicist will likely be able to respond to you more effectively!

The four fundamental forces that govern particle interactions in the universe are the gravitational, electromagnetic, weak nuclear, and strong nuclear forces. These forces were inferred from experimental observations and theoretical frameworks in physics, including general relativity and quantum field theory. Each force has a different range and strength.