A, B and C are hydroxy-compounds of the elements X, Y and Z respectively. X, Y and Z are in the same period of the periodic table. A gives an aqueous solution of pH less than seven. B reacts with both

Question

A, B and C are hydroxy-compounds of the elements X, Y and Z respectively. X, Y and Z are in the same period of the periodic table. A gives an aqueous solution of pH less than seven. B reacts with both strong acids and strong alkalis. C gives an aqueous solution which is strongly alkaline. Which of the following statements is/are true ? I : The three elements are metals. II : The electronegativities decrease from X to Y to Z. III : The atomic radius decreases in the order X, Y and Z. IV : X, Y and Z could be phosphorus, aluminium and sodium respectively.

Prashant Kotian · Accepted Answer

Correct answer: C. Step 1: Lawrencium (Lr, Z=103) is the final element in the actinide series located in the f-block of the 7th period. Step 2: Being the last actinide, its 5f subshell is fully filled with 14 electrons. Step 3: After filling the 5f subshell, the next incoming electron enters the 6d orbital. Thus, the correct outer electronic configuration of Lawrencium is [Rn] 5f14 6d1 7s2.

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