How strong is the attractive force of the nucleus on electrons?

Hint: In order to solve this question, we should know about nucleus and electrons in an atom. Nucleus consists of protons and neutrons while electrons keep moving in circular orbit around the nucleus and electrons are distributed in successive shells, here we will discuss the nucleus force on electrons.

Complete step by step answer:
As we can see, the nucleus consists of protons which have positive charge while electrons are of negative charge, so the force between nucleus and electrons is obviously attractive. Now, this attractive force between nucleus and electrons is generally determined by effective nuclear charge which is denoted by ${Z_{eff}}$ and this attractive force of nucleus on electrons decreases as we move away from the centre.
It’s because electrons are distributed in various successive shells in a tome and as we move outwards electrons before the targeted shell shields this force of attraction which in result it reduces the overall effective force and this effect is known as shielding effect.
so, net effective nuclear charge is calculated as ${Z_{eff}} = Z - S$ where Z is the number of protons called atomic number and S denotes the number of shielded electrons.
Hence, the attractive force of nucleus on electrons keeps on decreasing as we move outwards from the centre of an atom because the number of shielded electrons goes on increasing. It is strongest for the first shell electrons and then keeps decreasing.

Note: It should be remembered that, nuclear forces are very strong because they are very short ranges while most strongest force in nature is strong nuclear force and then successively strong forces are electromagnetic force, weak nuclear force and gravitational force is weakest among all four fundamental forces in nature.