Question

Which of the following is true about molecules?

1. Composed of the two same atoms

2. Composed of two different atoms

3. H2O is an example of molecule

4. All of the above is true.

Answer 1

4) All of the above is true.

Why?

When two or more atoms chemically bond together, they form a molecule. Sometimes the atoms are all from the same element. For example, when three oxygen atoms bond together, they form a molecule of ozone (O3). If a molecule forms from atoms of two or more different elements, we call it a compound. Every combination of atoms is a molecule. A compound is a molecule made of atoms from different elements. All compounds are molecules, but not all molecules are compounds. Hydrogen gas (H2) is a molecule, but not a compound because it is made of only one element. This is because they are all made up of different types of molecules. Molecules are not only made up of different types of atoms but also different ratios. Like in the water example above, a water molecule has 2 hydrogen atoms and 1 oxygen atom. This is written as H2O.

Sorry for the long paragraph. I wanted to get my point across.