NDA (II) 2024 GAT Q58: Which one among the following elements is

Q: What is the answer to NDA (II) 2024 GAT Q58?

B. Correct — B, Sulphur. Elemental sulphur exists as the S8 molecule — eight sulphur atoms joined in a puckered ring — so it is described as poly-atomic (its atomicity is 8). Among the options only sulphur carries this 'many-atom' molecule, which is why it is the polyatomic element. (Provisional — pending the official UPSC key.)

NDA (II) 2024 General Ability Test · Question 58 of 141

Question text verified against the official NDA question paper.

Provisional answers. UPSC has not yet released the official NDA 2024 answer key (it is published several months after the exam). The answers here are our best-supported answers — derived from careful subject-solving and cross-checked against independent solved papers and primary sources — and will be reconciled to the official key as soon as UPSC publishes it. They are not the official UPSC answer key.

Which one among the following elements is polyatomic?

(a)Phosphorus
(b)Sulphur
(c)Chlorine
(d)Aluminium

Answer

Why

Correct — B, Sulphur. Elemental sulphur exists as the S8 molecule — eight sulphur atoms joined in a puckered ring — so it is described as poly-atomic (its atomicity is 8). Among the options only sulphur carries this 'many-atom' molecule, which is why it is the polyatomic element.

Why the others are wrong

(a)Phosphorus — White phosphorus exists as the P4 molecule — four atoms — so it is specifically classed as tetra-atomic, not poly-atomic.
(c)Chlorine — Chlorine exists as the Cl2 molecule — two atoms — so it is diatomic, not polyatomic.
(d)Aluminium — Aluminium is a metal held in a giant metallic lattice; in chemical formulae its atomicity is taken as 1 (monatomic), so it is not a polyatomic molecular element.

Concept

Atomicity is the number of atoms present in one molecule of an element. Noble gases are monatomic; hydrogen, oxygen, nitrogen and the halogens (including Cl2) are diatomic; ozone (O3) is triatomic and white phosphorus (P4) is tetra-atomic; sulphur (S8) is the standard example of a poly-atomic element.

The trap is phosphorus: P4 does have four atoms, but the conventional table reserves 'tetra-atomic' for P4 and 'poly-atomic' for S8. So when a question asks for the polyatomic element, sulphur is the intended answer. Do not confuse a polyatomic element (S8) with a polyatomic ion (like SO4^2-).

Key facts

Atomicity = number of atoms per molecule of an element.
Sulphur molecule = S8 (poly-atomic, atomicity 8).
White phosphorus = P4 (tetra-atomic); chlorine = Cl2 (diatomic).
Metals such as aluminium are taken as monatomic (atomicity 1) in formulae.

A specimen of native sulphur showing bright-yellow crystals on a rock matrix — elemental sulphur occurs as bright-yellow crystals built from S8 ring molecules, the poly-atomic form of the elementImage: Ivar Leidus · Wikimedia Commons (CC BY-SA 4.0)

Study next

Atomicity table: monatomic, diatomic, triatomic, tetra-atomic, poly-atomicAllotropes of sulphur (rhombic and monoclinic) and of phosphorus (white, red, black)Difference between a polyatomic element (S8) and a polyatomic ion (SO4^2-, NO3-)Molecular versus giant/metallic structures

Common traps

Choosing phosphorus (P4) as 'polyatomic' — the table classes P4 specifically as tetra-atomic.
Confusing a polyatomic element (S8) with a polyatomic ion such as sulphate.

Asked directly as the atomicity of an element, or as 'give an example of a tetra-atomic / poly-atomic element'.

Related PYQs

No directly related past PYQ was found.

Practice

practice — not a real PYQ
The atomicity of ozone (O3) is:
- (a)1
- (b)2
- (c)3
- (d)4
Answer(c) 3 — ozone is a triatomic molecule made of three oxygen atoms.
practice — not a real PYQ
Which one of the following is a diatomic molecule?
- (a)Helium
- (b)Ozone
- (c)Chlorine
- (d)Phosphorus
Answer(c) Chlorine — chlorine exists as Cl2, two atoms per molecule.