which species represents a chemical compound?

Question

A) NH[subscript 4, superscript +]
B)N[subscript 2]
C)NaHCO[subscript 3]
D)Na

im kinda confused as to why i got this wrong on my chem test. please also give me a reason why the right answer is right

also, i put A and it was wrong

Answer 1

A. NH4+ is an ion. You can tell because of the + charge. It is not a compound because it can't exist in bulk form by itself; you need a - charge elsewhere to balance it out.

B. N2 is an element. You can tell because it has only one kind of atom (nitrogen). Compounds have at least two different types of elements.

D. Wrong, for same reason as B.

That leaves C as the right answer.

Answer 2

(A) That's an ion, its nitrogen with an additional proton (or more likely, one less electron).
(B) Is nitrogen an element
(D) Is sodium another element

(C) Is the correct answer.