(A) The position of an element in periodic table after emission of one `alpha` and two `beta`-partilce remians unchanged.
(R ) Emission of one `alpha` and two `beta` particles gives isotope of the parent element which acquires same position in the periodic table.

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 reasonb is false
D. If both assertion and reason are false.

Explanation

To solve the question regarding the assertion and reason statements about the emission of alpha and beta particles and their effect on the position of an element in the periodic table, we can break it down into the following steps:

### Step 1: Understand Alpha and Beta Emission
- **Alpha Emission**: When an element emits an alpha particle, it loses 2 protons and 2 neutrons. This results in a decrease of 2 in the atomic number (Z) and a decrease of 4 in the mass number (A).

- **Beta Emission**: When an element emits a beta particle, a neutron is converted into a proton, resulting in an increase of 1 in the atomic number (Z) while the mass number (A) remains unchanged.

### Step 2: Analyze the Changes from Emission
- **After one alpha emission**:
- New atomic number (Z) = Z - 2
- New mass number (A) = A - 4

- **After two beta emissions**:
- New atomic number (Z) = (Z - 2) + 2 = Z
- New mass number (A) = A - 4 (remains unchanged)

### Step 3: Determine the Final Position in the Periodic Table
- After the emissions, the atomic number returns to its original value (Z), meaning the element retains its original position in the periodic table.
- However, the mass number is reduced by 4, indicating that the new element is an isotope of the original element.

### Step 4: Evaluate the Assertion and Reason Statements
- **Assertion (A)**: The position of an element in the periodic table after emission of one alpha and two beta particles remains unchanged.
- **Reason (R)**: Emission of one alpha and two beta particles gives an isotope of the parent element which acquires the same position in the periodic table.

Both statements are true. The reason correctly explains the assertion since the atomic number remains the same while the mass number changes, resulting in an isotope of the original element.

### Conclusion
Thus, both the assertion and reason are true, and the reason is the correct explanation of the assertion.

### Final Answer
Both the assertion and reason are true, and the reason is the correct explanation of the assertion.

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