Question

Isotopes of an element have

• A. The same physical properties
• B. Different chemical properties
• C. Different number of neutrons
• D. Different atomic numbers.

Answer 1

The Correct Option is C

To understand the properties of isotopes and determine the correct answer, let's explore the concept of isotopes step-by-step:

1. Isotopes are variants of a particular chemical element that share the same number of protons but differ in the number of neutrons. This means they have the same atomic number but different mass numbers. 
2. Since the identity of an element is determined by the number of protons (also known as the atomic number), isotopes of an element do not have different atomic numbers. Hence, the option "Different atomic numbers" is incorrect.
3. Because isotopes have the same electron configuration (same number of electrons) as the parent element, they exhibit similar chemical behavior. Thus, the option "Different chemical properties" is incorrect.
4. The physical properties of isotopes, such as density and melting point, can differ due to the variation in mass numbers arising from different numbers of neutrons. However, this option isn't as defining as the number of neutrons when talking about isotopes specifically.
5. The defining characteristic of isotopes is that they have a "Different number of neutrons". Therefore, this is the correct answer.

Considering the above points, the correct answer is that isotopes of an element have a different number of neutrons.