Final answer:
An alkaline earth metal losing two electrons to gain a complete octet will have the same number of electrons as a noble gas.
Step-by-step explanation:
An alkaline earth metal is a group 2 element in the periodic table. These metals include elements like beryllium, magnesium, calcium, strontium, and barium. If an alkaline earth metal loses two electrons to gain a complete octet, it will have the same number of electrons as a noble gas.
For example, a neutral calcium atom with 20 electrons can lose two electrons to become a Ca2+ ion with 18 electrons. This ion has the same electron configuration as the noble gas argon.
Therefore, the answer is (a) Noble gas.