Answer:
3 of the 4 are elements
Step-by-step explanation:
An element can be found on the periodic table, and are only composed of one type of atom. For example, carbon is an element because you can find it on the periodic table. Fire isn't an element because you can't find it on the periodic table. A short-cut to see if something is an element is to look at the number of capital letters in the formula. If it only has one capital letter, it is an element. If it has two or more, it is a compound. This works because elements always have only one capitalized letter. For example, Ne has a capitalized N. O has a capitalized O. This only works if you are given the molecular formula and not the name, so looking at the periodic table is the best thing to do. Oxygen is an element, Sodium chloride is a compound, Gold is an element, and Neon is an element