The highest oxidation state of manganese in fluorides is indeed +4, as in MnF4, and the highest oxidation state in oxides is +7, as in Mn2O7. The reason for this difference is related to the chemistry of fluorine and oxygen and their interactions with manganese.
The correct answer to the question is (B) Fluorine doesn't possess d orbitals.
Here's an explanation of why this is the case:
(A) Fluorine is most electronegative than oxygen.
This statement is true; fluorine is indeed more electronegative than oxygen. However, electronegativity does play a role in determining oxidation states, but it is not the primary reason for the difference in oxidation states between fluorides and oxides.
(B) Fluorine doesn't possess d orbitals.
This is the key reason for the difference in oxidation states. In chemical reactions, elements can lose or gain electrons from their outermost electron orbitals, which are the s and p orbitals for the main-group elements. However, for transition metals like manganese, the d orbitals also come into play in bonding and electron transfer.
Oxygen has only two valence electrons in its outermost energy level (2p), so it can gain electrons to achieve a full valence shell (usually gaining two electrons to form an oxide ion, O^2-). Fluorine, on the other hand, has seven valence electrons in its outermost energy level (2s^2 2p^5). It is highly electronegative and readily accepts one electron to complete its valence shell (forming a fluoride ion, F^-). Since fluorine lacks d orbitals in its valence shell, it cannot accommodate higher oxidation states by accepting more electrons.
(C) Fluorine stabilizes lower oxidation states.
This statement is generally true. Fluorine is a very strong oxidizing agent and tends to stabilize lower oxidation states in other elements.
(D) In covalent compounds, fluorine can form a single bond only while oxygen forms a double bond.
This statement is not entirely accurate. Both fluorine and oxygen can form single bonds in covalent compounds, and both can also form multiple bonds. The ability to form multiple bonds depends on the number of available valence electrons and the electronegativity of the elements involved.
In summary, the primary reason for the difference in oxidation states between manganese fluorides and oxides is that fluorine lacks d orbitals in its valence shell, limiting its ability to accommodate higher oxidation states.
