(C) A metal 'M' has electronic configuration 2, 8, 2. Find the formula of its 12]
a. Hydroxide
b. Phosphate

M = 2 . 8 . 2

Valence Electron of M = 2

M ==>  M⁺²  +  2 e⁻

a. M⁺² +  OH⁻   ==>   M(OH)₂

b. M⁺² +  PO₄⁻³  ==>  M₃(PO₄)₂

it is a good conductor

explanation:

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"