Consider the following elements.
Group, |, A′ B′, → Period; ↓, C′ D′
Which of the following is/are true about A′, B′, C′ and D′ ?
A. Order of atomic radii: B′<A′<D′<C′
B. Order of metallic character: B′<A′<D′<C′
C. Size of the element: D′<C′<B′<A′
D. Order of ionic radii: B^(′+)<A^(1⁺)<D^(′+)<C⁺
Choose the correct answer from the options given below :

Solution

Chemistry ma’am · 3 steps

Place the four letters on a grid: size grows going down a group and shrinks going right along a period.

1. Read the grid. A′ and B′ are in the same period, with B′ to the right. C′ and D′ are in the next period, directly below A′ and B′. So C′ is the lower-left corner and B′ is the upper-right corner.
2. Size trend. Across a period the nuclear charge rises, so B′ < A′ and D′ < C′. Down a group a new shell is added, and that jump is larger than one step across, so D′ > A′. For example, Be 111 pm, Li 152 pm, Mg 160 pm, Na 186 pm.

   Statement	Claimed order	Verdict
   A: atomic radii	B′ < A′ < D′ < C′	True, it matches the size trend
   B: metallic character	B′ < A′ < D′ < C′	True, bigger atoms lose electrons more easily
   C: size	D′ < C′ < B′ < A′	False, it makes the lower period smaller
   D: radii of +1 ions	B′⁺ < A′⁺ < D′⁺ < C′⁺	True, ions of the same charge follow the atom trend

3. So. Statements A, B and D are correct and C is wrong, so the answer is (d).

The idea to keep. On a 2 × 2 block of the periodic table, the lower-left element is the largest and most metallic, and the upper-right one is the smallest. Ions of equal charge follow the same order.

Answer from the NTA final answer key. Solution by PrepWiser.