Question

Isotopes of an element have:
A.The same physical properties
B.Same chemical properties
C.Different number of neutrons
D.Different atomic numbers

Answer 1

Hint: The chemical properties of isotopes depend on their number of electrons, number of valence electrons, and atomic number. The physical properties are based on their atomic mass.

Complete answer:
- Isotopes are the different atoms of the same atom. Hence, they have the same atomic number.
- But isotopes differ in the mass number/ atomic mass. For example, three isotopes hydrogen, deuterium, and tritium have the same atomic number of 1. But they have different atomic masses. The atomic mass of hydrogen, deuterium, and tritium are 1, 2, and 3 respectively.
- The atomic number is equal to the number of protons, and electrons in a neutral atom.
- The chemical property of an atom is the ability of the atom to react with another atom or molecule.
- Since, the atomic number of different isotopes is the same, the number of electrons is also the same. Hence, isotopes have the same chemical properties.
- Isotopes have different mass numbers and different atomic masses. Hence, isotopes have different physical properties. Mass number is equal to the sum of the number of protons and the number of neutrons.

Therefore, the answer to the question is option (B) Same chemical properties and (C) Different number of neutrons.

Note:
It is observed that different isotopes undergo the same reaction at different reaction rates. This is because different isotopes have different activation energy. This phenomenon is known as isotopic effect.