The increasingorder of atomicradii of the followinggroup 13 element is

1.	The increasingorder of atomicradii of the followinggroup 13 element is
Answer» `Al lt GA lt In lt Tl` `Ga lt Al lt In lt Tl` `Al lt In lt Ga lt Tl` `Al lt Ga ltTl lt In` Solution :Due to ineffectiveshielding of 3d-orbitals , theeffective nuclearcharge of GAIS greater in magnitudethanof Al. As a result,ATOMIC radii ofFa is lower thanthat of Al.The atomic radiiof remaining elementincreases regularly as we movedown the group from LN to Tl. Thus,atomic radii of the four elements from Al to Tl increase in the order : `Ga lt Al lt In lt Tl`, i.e.,OPTION(b) is correct.

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