Which sodium compound contains the greatest percentage by mass of sodium?
[Relative atomic masses, ArA_rAr: H=1.0\text{H} = 1.0H=1.0; C=12.0\text{C} = 12.0C=12.0; O=16.0\text{O} = 16.0O=16.0; Na=23.0\text{Na} = 23.0Na=23.0; Cl=35.5\text{Cl} = 35.5Cl=35.5]
sodium oxide
sodium chloride
sodium hydroxide
sodium carbonate
