Assertion : Isotopes are electrically neutral. Reason : Isotopes are species with same mass number but different atomic numbers.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Explanation

To analyze the assertion and reason provided in the question, let's break it down step by step.

### Step 1: Understanding the Assertion
**Assertion:** Isotopes are electrically neutral.

- Isotopes are variants of the same element that have the same number of protons (which defines the element) but different numbers of neutrons.
- Since isotopes have the same number of protons and electrons, they are electrically neutral. The positive charge from protons is balanced by the negative charge from electrons.

### Step 2: Understanding the Reason
**Reason:** Isotopes are species with the same mass number but different atomic numbers.

- This statement is incorrect. Isotopes have the same atomic number (which means they are the same element) but different mass numbers due to the different number of neutrons.
- The atomic number is the number of protons in the nucleus, while the mass number is the total number of protons and neutrons.

### Step 3: Conclusion
- The assertion is **true** because isotopes are electrically neutral.
- The reason is **false** because isotopes have the same atomic number, not the same mass number.

### Final Answer
- The assertion is true, and the reason is false.

---