Assertion: Isotopes of an element have the same chemical properties. Reason: Chemical properties do not depend on the number of neutrons. (A) Both Assertion and reason are correct and the reason is the correct explanation of the assertion. (B) Both Assertion and reason are true but reason is not the correct explanation of Assertion. (C) Assertion is incorrect but reason is correct. (D) Assertion is correct but reason is correct.
Hint :Isotopes are the two or more types of atoms that have the same atomic number but different atomic weight. Thus, isotopes lie at the same position in the periodic table and have the same chemical properties.
Complete Step By Step Answer: As we know, isotopes have the same atomic number and different atomic mass. This means that the number of electrons and protons in the isotopes of the element is the same but the number of neutrons present in them is different. So looking at our Assertion – Since, the electronic configuration of the isotopes are same and chemical properties of the element is a characteristic of its electronic configuration. Thus, we can say that Isotopes of an element have the same chemical properties. Therefore, our Assertion is correct. Now, coming to our Reason – it says that chemical properties do not depend on the number of neutrons. As we know that physical properties are defined by the mass of element i.e. different number of neutrons. Therefore our Reason is also correct. But as we know that chemical properties depend on electronic configuration and physical properties depend on the number of neutrons. So Reason is not the correct explanation of the Assertion. Therefore, correct option is B i.e. Both Assertion and reason is true but reason is not the correct explanation of Assertion.
Note : Atomic number of the element is defined by the proton more accurately in the ion, as the number of electrons keeps on varying in the ion as they keep on moving in different energy level shells and are busy in making bonds with other atoms.