Multiple Choice
Which term is used to describe the rows of the periodic table?
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2. Atoms & Elements
Periodic Table: Classifications
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Which of the following pure substances can be classified as an element?
A
Carbon dioxide (CO2)
B
Sodium chloride (NaCl)
C
Water (H2O)
D
Oxygen (O2)
Verified step by step guidance1
Understand the definition of an element: An element is a pure substance that consists of only one type of atom. It cannot be broken down into simpler substances by chemical means.
Analyze each substance given in the problem: Carbon dioxide (CO2), Sodium chloride (NaCl), Water (H2O), and Oxygen (O2).
Identify the composition of each substance: CO2 contains carbon and oxygen atoms bonded together, NaCl contains sodium and chlorine ions, H2O contains hydrogen and oxygen atoms, and O2 consists of only oxygen atoms bonded together.
Determine which substances are compounds and which are elements: Compounds are substances made of two or more different elements chemically combined, while elements contain only one type of atom.
Conclude that Oxygen (O2) is the only pure substance listed that is an element because it contains only one type of atom, oxygen, whereas the others are compounds.
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