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Assertion : Atomic radius of gallium is ...

Assertion : Atomic radius of gallium is higher than that of aluminium
Reason : The presence of additional d-electron offer poor screening effect for the outer electrons from increased nuclear charge.

A

Assertion is correct, reason is correct, reason is a correct
explanation for assertion.

B

Assertion is correct, reason is correct, reason is not a correct explanation for assertion

C

Assertion is correct, reason is incorrect

D

Assertion is incorrect, reason is correct.

Text Solution

AI Generated Solution

The correct Answer is:
To solve the question, we need to analyze both the assertion and the reason provided. ### Step 1: Understand the Assertion The assertion states that the atomic radius of gallium is higher than that of aluminium. - **Gallium (Ga)** and **Aluminium (Al)** are both in Group 13 of the periodic table. - Generally, as we move down a group in the periodic table, the atomic radius increases due to the addition of electron shells. However, gallium is an exception to this trend. ### Step 2: Compare Atomic Radii - The atomic radius of aluminium is approximately 143 pm (picometers), while that of gallium is about 135 pm. - Therefore, the assertion that the atomic radius of gallium is higher than that of aluminium is **incorrect**. ### Step 3: Understand the Reason The reason states that the presence of additional d-electrons offers a poor screening effect for the outer electrons from increased nuclear charge. - Gallium has an additional d-electron compared to aluminium. This d-electron does not effectively shield the outer electrons from the increased nuclear charge. - The presence of these d-electrons leads to a phenomenon known as "poor shielding," which contributes to the smaller atomic radius of gallium compared to aluminium. ### Step 4: Conclusion - The assertion is **incorrect** because gallium's atomic radius is actually smaller than that of aluminium. - The reason is **correct** as it explains why gallium has a smaller atomic radius due to the poor screening effect of the d-electrons. ### Final Answer - Assertion: Incorrect - Reason: Correct
To solve the question, we need to analyze both the assertion and the reason provided. ### Step 1: Understand the Assertion The assertion states that the atomic radius of gallium is higher than that of aluminium. - **Gallium (Ga)** and **Aluminium (Al)** are both in Group 13 of the periodic table. - Generally, as we move down a group in the periodic table, the atomic radius increases due to the addition of electron shells. However, gallium is an exception to this trend. ...
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