A group goes vertically and a period goes horizontally.
(a group goes down and a period goes across)
Answer:
MgO- magnesium oxide
Cu(NO3)2- copper(11)nitrate
Li2CO3- lithium carbonate
A - 1 CH4+ 1 O2 = 1 CO2+2 H2
b - 2 Al+3 Cl2 = 2 AlCl3
c - 1 CH2O+ 1 H2 = 1 CH3OH
*The ones that have the coefficient of 1 you can leave blank but if you have to put a number just put 1