SSC CGL 2024 Tier-I · 13 September 2024, Shift 2 · General Awareness · Question 20 of 99

Text as printed on a candidate's response sheet for this shift; answer per SSC's tentative key as marked on that sheet. Solution last reviewed 10 September 2026.

Where this paper and its answers come from

SSC does not publish CGL question papers or a public answer key. The questions and options here are reproduced as printed on a candidate's own response sheet for this shift — the Commission's text, unchanged. Each answer is SSC's tentative key as marked on that sheet; SSC allowed challenges to it and never publishes a final key. The solutions are written by UnlockIAS.

Transition elements are the elements that are found in Groups 3-12 of the modern periodic table, that constitute the _____.

(a)f-block
(b)d-block
(c)p-block
(d)s-block

Answer

Why

Correct — B. Groups 3 to 12 are the columns in which the d orbitals are being filled, so those elements make up the d-block.

A transition element is defined by a partly filled d subshell, either in the atom or in one of its common ions. That is the middle slab of the table — scandium to zinc in period 4, and the rows beneath it.

The stem's own phrase, Groups 3-12, fixes the block: option (b).

Why the others are wrong

(a)
f-block — The f-block is the lanthanides and actinides, the two rows printed below the main table. They are the inner transition elements and do not occupy Groups 3 to 12.
(c)
p-block — The p-block is Groups 13 to 18, where p orbitals fill — boron across to neon and the columns below. It lies to the right of the transition metals.
(d)
s-block — The s-block is Groups 1 and 2, the alkali and alkaline earth metals on the far left. Its elements have no partly filled d subshell.

Concept

The modern periodic table is read in blocks, each named for the subshell the differentiating electron enters.

s-block is Groups 1 and 2. p-block is Groups 13 to 18. d-block is Groups 3 to 12. f-block is the lanthanides and actinides, printed separately below.

The d-block is where variable oxidation states, coloured ions, catalytic activity and complex formation come from — all consequences of a partly filled d subshell.

Strictly, zinc, cadmium and mercury sit in Group 12 and in the d-block, yet they are usually excluded from the transition series because their d subshell is full both in the atom and in the common +2 ion.

The stem equates Groups 3-12 with the d-block, and the key follows that equation.

Key facts

Groups 3 to 12 of the modern periodic table form the d-block.
A transition element has a partly filled d subshell in its atom or in a common ion.
Zinc, cadmium and mercury are d-block elements but are usually not counted as transition elements.
The lanthanides and actinides make up the f-block, the inner transition elements.

Study next

Electronic configurations of the first transition series, scandium to zincWhy transition metal ions are coloured and show variable oxidation statesLanthanide contraction and the inner transition elements

Common traps

Reading 'transition' as 'in between' and choosing the p-block that separates metals from non-metals.
Counting zinc as a transition element without checking whether its d subshell is full.

SSC works the periodic table from its history as much as from its structure — Mendeleev's predicted atomic mass for eka-aluminium is asked at 19 Sep 2024, 12:30, GA Q.18, and eka-silicon is matched to germanium at 25 Sep 2024, 09:00, GA Q.25.

Related PYQs

No directly related past PYQ was found.