Answer:
Ca = 1s²2s²2p⁶3s²3p⁶4s²
Explanation:
Calcium is located in the second column and the 4th row of the periodic table. Thus, there are 2 valence electrons and the highest quantum number is 4. This is represented by 4s². However, all of the previous orbitals and electrons must be listed beforehand, making the entire electron configuration: 1s²2s²2p⁶3s²3p⁶4s².
A or D I think...sorry if it’s wrong
Answer:

Explanation:
Hello,
Based on the given reaction, since magnesium and water are in a 1:2 molar ratio at the reactants, we must apply the following stoichiometric factors to compute the complete reaction of the 6.0 g of magnesium:

Best regards.
The molarity is 31.0 * x / 2, such that x is the molar mass of Ca₃(PO₄)₂