Question

An element naturally occurs in two isotopic forms. Which of the following statements is correct?

• A. Mass number of the two isotopes are same.
• B. Atomic number of the two isotopes are same.
• C. Number of nucleons are same.
• D. Number of neutrons are same.

Hint:

Isotopes = same protons (Z), different neutrons → different mass numbers.

Answer 1

The Correct Option is B

Step 1: Definition of isotopes.
Isotopes are atoms of the same element that have the same atomic number (same protons) but different mass numbers (different neutrons).
Step 2: Analyze options.
- (1) Wrong: mass number differs in isotopes.
- (2) Correct: atomic number is identical (same element).
- (3) Wrong: nucleon number (mass number) differs.
- (4) Wrong: neutrons differ.
Final Answer: \[ \boxed{\text{Atomic number of the two isotopes are same}} \]