The atomic number, Z, is the integer number of protons found in the atomic nucleus of a particular chemical element. Suppose a first atom has atomic number 3. Additionally suppose that this particular atom is fully ionized, meaning that all of its electrons have been removed, so it is a bare nucleus.
What is the magnitude of the electric field, in newtons per coulomb, at distance of 1×10−10m from the fully ionized atom with atomic number 3?