Question

Compounds have:
(A) Only one kind of atoms
(B) Only one kind of elements
(C) Only one kind of molecules
(D) Atoms from different elements combined in fixed ratio

Answer 1

Hint: Chemical compound is a chemical substance which is made up of many identical molecules and those molecules consist of atoms. We can say that molecular oxygen ($O_2$) is not a compound but water $(H_{2}O)$ is a compound.

Complete Step-by-Step Solution:
We will get some information about chemical compounds.
- Chemical compound is a chemical substance which is made up of many identical molecules and those molecules consist of atoms of more than one element held together by different types of chemical bonds.
- So, the molecules need to be made up of more than one type of elements in the case of compounds. So, the molecules which have only one type of element cannot be considered as compounds.
e.g. molecular oxygen ($O_2$)
- The number of different atoms present in the compound may differ as the compound changes. Chemical formula shows the number of atoms present in a particular molecule of the compound.
e.g. We can say that $H_{2}O$ is a compound because it is made up of two different elements; hydrogen and oxygen.
- Depending upon the type of bond present in the compound, it can be divided into certain categories like molecules, ionic compounds, intermetallic compounds and complexes.
Thus, we can conclude that compounds have atoms from different elements combined in a fixed ratio.

So, the correct answer of the question is (D).

Note: Do not get confused between compounds and molecules. All molecules cannot be considered as compounds. e.g.$O_2,H_2$ , etc. Same way, all compounds cannot be considered molecules as well. e.g. NaCl