Answer: The given element belongs to Period 4.
Step-by-step explanation:
We are given:
Number of innermost electrons = 28
Number of outermost electrons = 7
Total number of electrons = 28 + 7 = 35
Electronic configuration is defined as the representation of electrons around the nucleus of an atom.
Number of electrons in an atom is determined by the atomic number of that atom.
The electronic configuration of the element having atomic number '35' is:

To identify the period, we look at the highest occupied principle quantum number which is 'n'. Here, the value of highest occupied shell or 'n' is 4.
Hence, the given element belongs to Period 4.