Answer:
O(Oxygen)
Explanation:
2+2+4=8
And the eighth element of the periodic table is Oxygen
Formaldehyde is an organic compound.
In order to get HgO you would need 2Hg+1O2=2HgO. Since oxygen is diatomic you need two when it stands alone causing you to need two mercuries to balance out the reactants and the product I hope this helps
A Physical Change is what the change of ice is
The answer is 25 grams for this question