The question is incomplete, the elements to be arranged as required are shown in the image attached to this answer.
Answer:
K<Mg<P<O
Explanation:
Electronegativity is the ability of an atom of an element in a compound to attract the shared electrons of a bond towards itself. Atoms of highly electronegative elements tend to polarize a covalent bond leading to polar covalent bonds and dipole moments. Electronegativity increases across the period but decreases down the group hence the arrangement of elements in the answer provided above.
CuSO4 *5H20 In the formula of the hydrate, on the first place is the salt and on the second of water. so in ration on the first place should be salt also.