a) 2 atoms . so if you do 2 out of 100 it will be 2%. plus the hydrogen 4% = 6%
b) 1 atom so 1% . plus the hydrogen 3% = 4%
c) 2 atoms so 2% . plus the oxygen 4% = 6%
d) 1 atom so 1% . plus sodium 1% plus oxygen 3% = 5%
so the compound with the greatest percentage is a & c
idk if this is right i haven’t learnt this in school i googled this
