Which of the following complex will show largest splitting of d-orbitals?

Which of the following are the example of double salt?

A. $$\mathrm{FeSO}_{4} \cdot\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4} \cdot 6 \mathrm{H}_{2} \mathrm{O}$$

B. $$\mathrm{CuSO}_{4}\cdot 4 \mathrm{NH}_{3} \cdot \mathrm{H}_{2} \mathrm{O}$$

C. $$\mathrm{K}_{2} \mathrm{SO}_{4} \cdot \mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3} \cdot 24 \mathrm{H}_{2} \mathrm{O}$$

D. $$\mathrm{Fe}(\mathrm{CN})_{2}\cdot4 \mathrm{KCN}$$

Choose the correct answer :

Highest oxidation state of Mn is exhibited in $$\mathrm{Mn_2O_7}$$. The correct statements about $$\mathrm{Mn_2O_7}$$ are

(A) Mn is tetrahedrally surrounded by oxygen atoms.

(B) Mn is octahedrally surrounded by oxygen atoms.

(C) Contains Mn-O-Mn bridge.

(D) Contains Mn-Mn bond.

Choose the correct answer from the options given below :

The correct representation in six membered pyranose form for the following sugar [X] is