Question

Assertion (A) : All isotopes of a given element show the same type of chemical behaviour.

Reason (R) : The chemical properties of an atom are controlled by the number of electrons in the atom.

• A. Both A and R are true and R is the correct explanation of A.
• B. Both A and R are true but R is not the correct explanation of A
• C. A is true but R is false.
• D. Both A and R are false.

Answer 1

The correct option is A Both A and R are true and R is the correct explanation of A.

Analyzing the assertion

Assertion:

All isotopes of a given element show the same type of chemical behaviour.

An isotope is defined as the compound which has the same atomic number and different atomic masses thus Isotope of an element has same number of electrons and protons but different number of neutrons.

Analyzing the reason

Reason:

The chemical properties of an atom are controlled by the number of electrons in the atom

For any neutral ground state atom: Atomic number = number of protons = number of electrons

Isotopes have same atomic number thus they have same number of protons and electrons as well.

The chemical properties are governed by number of electrons (i.e. atomic number) in the atom and since isotopes have the same atomic number, thus they show same type of chemical behaviour.

Conclusion

Assertion and reason both are correct, and reason is the correct explanation of assertion.

Hence, the correct option is (A)