Question

Assertion: An atom is the smallest particle in an element that has the properties of the element.
Reason: Molecules are formed by the combination of two or more atoms.
(a) Both Assertion and Reason are correct and Reason is the correct explanation of
Assertion
(b) Both Assertion and Reason are correct but Reason is not the correct explanation of
Assertion.
(c) Assertion is correct but Reason is incorrect.
(d) Both Assertion and Reason are incorrect.

Answer 1

Hint: Dalton’s atomic theory specified many postulates which clearly tells about and atoms and molecules. It provides a basis for distinguishing between elements and compounds. Also, it does not violate several fundamental laws of chemical combination such as the law of definite proportions, the law of multiple proportions and the law of conservation of mass.

Complete Step by step answer:
We have two statements given here one is about atoms and one is about molecules. Both of them are related to Dalton’s atomic theory. Therefore, we can look into Dalton’s atomic theory.

In Dalton’s postulates it clearly says that atoms of a specific element are identical in mass, size and other properties but atoms of different elements exhibit different properties and vary in mass and size. Also, it states that matter is made up of tiny, indivisible particles called atoms. Hence, from these two postulates we understood that the atom is the smallest particle in an element and it has all the properties of an element. Therefore, Assertion is correct.

Now coming to Reason. In Dalton’s atomic theory it states that atoms of different elements can combine with each other in fixed whole-number ratios in order to form compounds. We know that all compounds are molecules, hence this is the same as molecules also. Therefore, we can conclude from this that molecules are formed by the combination of two or more atoms. Hence Reason is also correct
But Reason is not the correct explanation of Assertion they both are just two postulates of Dalton’s atomic theory. That is why we say Reason is not the correct explanation of Assertion

Hence the option (b) is correct.

Note: Here, we choose Dalton’s atomic theory to explain the reasons behind this but in the first statements it says atom is the smallest particle which is not entirely correct as we know there are sub particles also such as electrons, protons and neutrons. These statements are purely based on Dalton’s atomic theory and it has many limitations which have been overcome by the other atomic theories and structures.