Question:medium

Consider the following statements:
Statement I: Stability of +1 oxidation state increases down the group in group-13.
Statement II: Atomic radius of Ga is greater than that of Al.

Updated On: Feb 25, 2026
  • Both statements 1 and 2 are true and statement 2 is the correct explanation of statement 1.
  • Both statements 1 and 2 are true and statement 2 is not the correct explanation of statement 1.
  • Statement 1 is true but statement 2 is false.
  • Statement 1 is false but statement 2 is true.
Show Solution

The Correct Option is C

Solution and Explanation

The question presents two statements related to the chemistry of Group 13 elements. Let's evaluate each statement to determine their accuracy.

  1. Analysis of Statement I: "Stability of +1 oxidation state increases down the group in group-13."
    • Group 13 elements (Boron, Aluminum, Gallium, Indium, and Thallium) primarily exhibit +3 oxidation states. However, the +1 oxidation state becomes more stable as we move down the group due to the inert pair effect.
    • This effect is more pronounced in heavier elements due to the reluctance of s electrons to participate in bonding as nuclear charge increases.
    • As a result, for heavier elements like Thallium (Tl), the +1 oxidation state is more stable than the +3 state.
    • Therefore, Statement I is true.
  2. Analysis of Statement II: "Atomic radius of Ga is greater than that of Al."
    • Normally, atomic size increases down a group due to the addition of electron shells. However, in Group 13, Gallium (Ga) has a comparable or slightly smaller atomic radius than Aluminum (Al).
    • This anomaly is due to the presence of d-electrons in Gallium, which do not shield the nuclear charge very effectively, pulling outer electrons closer to the nucleus.
    • Consequently, the atomic radius of Ga is in fact slightly less than or similar to Al.
    • Thus, Statement II is false.

Based on the analysis:

  • Statement I is true as the stability of the +1 oxidation state increases down the group in Group 13.
  • Statement II is false because the atomic radius of Gallium is not greater than that of Aluminum.

The correct option is: "Statement 1 is true but statement 2 is false."

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