Refer to the illustration of the periodic table to determine which formula is correct.
Mg3O2
Mg2O
MgO2
MgO

D. MgO

Explanation:

We need to look at the charge of element. (Look at a periodic table for this)

Mg, which is Magnesium, has a charge of 2+ because it's in the second column, or group, from the left.

O, which is Oxygen, has a charge of 2- because it's in the second column, or group, from the right.

Since Mg is 2+, it's the cation and since O is 2-, it's the anion. We can put these two elements together into an ionic compound.

Mg^(2+) and O^(2-) becomes Mg2O2, where we can cancel the 2s: MgO.

Thus, the answer is D.

Hope this helps!

answer; ///i do believe that the correct answer is (b); ///particle composed of two or more atoms bonded together;

"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"