The formulae of the five most abundant substances in air are shown:
N₂ O₂ Ar CO₂ H₂O
How many of these five substances are elements and how many of these five substances are made of molecules?
A) Elements = 1, molecules = 4
B) Elements = 1, molecules = 2
C) Elements = 5, molecules = 4
D) Elements = 3, molecules = 2
E) Elements = 3, molecules = 4
IMAT 2023 · Question 42
Q42 - Compounds and elements
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The correct answer is E) Elements = 3, molecules = 4.
Elements are made of one kind of atom: N₂, O₂ and Ar, so 3.
Molecules need at least two atoms bonded together: N₂, O₂, CO₂ and H₂O, so 4. Argon is a noble gas and exists as single atoms.
3 elements, 4 molecules.
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