Explanation:
When two elements combine to form a compound, they do so in a way that allows them to achieve a stable electron configuration. This is typically done by either transferring or sharing electrons.

Electron Configuration:
In this case, Element P has 2 electrons in its outermost shell, while Element Q has 6 electrons in its outermost shell. Both elements want to achieve a stable electron configuration, which typically involves having a full outermost shell with 8 electrons.

Formation of Compound:
To achieve a stable electron configuration, Element P can transfer its 2 electrons to Element Q. This will result in Element P having a full outermost shell (with 8 electrons) and Element Q also having a full outermost shell (with 8 electrons).

The compound formed by the transfer of electrons from Element P to Element Q will have the formula PQ.

Explanation of Options:
a) PQ: This is the correct answer as explained above.
b) P2Q: This formula suggests that there are two atoms of Element P and one atom of Element Q. However, the question states that there are only two electrons in the outermost shell of Element P, which is not consistent with having two atoms of Element P.
c) P2Q3: This formula suggests that there are two atoms of Element P and three atoms of Element Q. Again, this is not consistent with the information given in the question.
d) PQ2: This formula suggests that there is one atom of Element P and two atoms of Element Q. However, the question states that there are only two electrons in the outermost shell of Element P, which is not consistent with having two atoms of Element Q.

Therefore, the correct formula of the compound formed by the combination of Element P and Element Q is PQ.