Question

How can you say that Oxygen gas is an element and water is a compound? ​

Answer 1

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A compound forms whenever two or more atoms form chemical bonds with each other. The chemical formula for water is H2O, which means each molecule of water consists of one oxygen atom chemically bonded to two hydrogen atoms. Thus, water is a compound

Oxygen in the atmosphere is a molecule because it contains molecular bonds. It is not a compound because it is made from atoms of only one element - oxygen. This type of molecule is called a diatomic molecule, a molecule made from two atoms of the same type.

Answer 2

Answer:

oxygen gas have got only oxygen atom so it's a pure form of elements

water is mixture of hydrogen and oxygen in the ratio of 2:1 and this says that it is a compound