Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: Assertion A: Loss of electron from hydrogen atom results in nucleus of `~1.5 × 10^(–3)` pm size.
Reason R: Proton `(H^+)` always exists in combined form.
In the light of the above statements, choose the most appropriate answer from the options given below:

Options

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

Answer

To solve the question, we need to analyze both the Assertion (A) and the Reason (R) provided.

### Step 1: Analyze the Assertion (A)
The assertion states: "Loss of electron from hydrogen atom results in nucleus of `~1.5 × 10^(–3)` pm size."

- When a hydrogen atom loses its electron, it becomes a proton (H⁺). The size of the nucleus of a hydrogen atom (which is essentially a single proton) is indeed very small, around `1.5 × 10^(–3)` pm (picometers).
- Therefore, the assertion is **correct**.

### Step 2: Analyze the Reason (R)
The reason states: "Proton (H⁺) always exists in combined form."

- This statement is generally true. In nature, free protons (H⁺ ions) do not exist independently for long periods; they tend to combine with other atoms or molecules, such as in acids or in the formation of hydrogen gas (H₂).
- Thus, the reason is also **correct**.

### Step 3: Determine the Relationship Between A and R
Now we need to determine if the reason provided is the correct explanation for the assertion.

- The assertion talks about the size of the nucleus after the loss of an electron, while the reason discusses the behavior of protons in nature.
- The reason does not explain why the size of the nucleus is `~1.5 × 10^(–3)` pm. Therefore, while both statements are correct, the reason does not provide a valid explanation for the assertion.

### Conclusion
Based on the analysis:
- Both the assertion and the reason are correct.
- However, the reason is not the correct explanation for the assertion.

Thus, the most appropriate answer is: **Option 4: Both assertion and reason are correct, but reason is not the correct explanation of assertion.**

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