B. Hydrogen is the answer
The element is TELLURIUM. Tellurium has atomic number 52 with the electronic configuration of [Kr] 4d10 5s2 5p4. The element belongs to group 16 elements on the periodic table. It exhibits various oxidation states: +2, +4, +6, and -2. +4 is its most common oxidation state.
Since the given formula is . According to cross method formula, magnesium has +2 charge so, is multiplied by 2.
Thus, 1 molecule of magnesium phosphate will contain 2 atoms of phosphorus.
Therefore, three molecules of magnesium phosphate contains following number of atoms.
Mg = 9
P = 6
O = 24
Hence, we can conclude that there are 6 atoms of phosphorus in three molecules of magnesium phosphate, .
