In each of the following question a statement of assertion is given followed by a corresponding statement of reason just below it of the statement mark the correct answer as
Assertion(A) All the isotopes of a given element show some chemical behaviour
Reason (R) number of neutrons have a negligible effect on the chemical properties of an element

Options

A. Both A and R are true and R is the correct explanation of A
B. Both A and R are true and R is not the correct explanation of A
C. A is true but R is false
D. A is false but R is true

Answer

To analyze the given assertion and reason, we will break down the statements step by step:

### Step 1: Understand the Assertion
- **Assertion (A)**: "All the isotopes of a given element show some chemical behaviour."
- Isotopes are variants of the same element that have the same number of protons (same atomic number) but different numbers of neutrons (different mass numbers).
- Since isotopes of an element have the same atomic number, they exhibit similar chemical properties.

### Step 2: Understand the Reason
- **Reason (R)**: "Number of neutrons have a negligible effect on the chemical properties of an element."
- The chemical properties of an element are primarily determined by the arrangement of electrons, which is influenced by the number of protons (atomic number).
- Neutrons, while they affect the mass and stability of the nucleus, do not significantly influence the chemical behavior of the element.

### Step 3: Evaluate the Truth of Each Statement
- The assertion is **true** because all isotopes of an element have the same chemical behavior due to their identical atomic number.
- The reason is also **true** because the number of neutrons does not significantly affect the chemical properties, which are determined by the atomic number.

### Step 4: Determine the Relationship Between Assertion and Reason
- The reason provided correctly explains why the assertion is true. The reason clarifies that the chemical properties are determined by the atomic number, which remains constant among isotopes.

### Conclusion
Since both the assertion and reason are true, and the reason correctly explains the assertion, the correct answer is:
- **Option 1**: Both assertion and reason are true, and the reason is the correct explanation of the assertion.

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