NEET Chemistry — Inorganic Chemistry Chapter Guide

Chapter Overview & Weightage

Inorganic Chemistry is NEET’s most reliable scoring zone. Every single year, 10–12 questions appear from this area — that’s roughly 40–48 marks out of 180. For many toppers, this chapter block is where they build their safety net.

The distribution has stayed consistent over the past five years:

Year	Questions	Marks	Key Topics That Dominated
2024	11	44	p-Block, Coordination, Periodic Trends
2023	12	48	d-Block, Metallurgy, Hydrogen
2022	10	40	p-Block, Coordination, s-Block
2021	11	44	Periodic Trends, p-Block, d-Block
2020	12	48	Coordination, p-Block, Metallurgy

p-Block Elements alone accounts for 4–5 questions every year. If you’re short on time, p-Block + Coordination Compounds gives you the best return per hour of study.

The entire inorganic section rewards systematic memorisation backed by conceptual understanding. Unlike Physical Chemistry where you calculate, here you identify patterns and recall facts with reasoning.

Key Concepts You Must Know

Ranked by NEET frequency — do not skip the top items:

Tier 1 — Appears Every Year

Periodic trends: ionisation enthalpy, electron gain enthalpy, electronegativity, atomic/ionic radii — including anomalies (N > O, F > Cl for electron gain)
p-Block: Group 15, 16, 17 properties, oxoacids of nitrogen, sulphur, phosphorus, halogens
Coordination Compounds: IUPAC naming, CFT (crystal field theory), colour and magnetic properties
d & f Block: Electronic configurations, variable oxidation states, catalytic properties of transition metals

Tier 2 — 2–3 Questions Most Years

s-Block: Anomalous behaviour of Li and Be, diagonal relationships, uses of compounds (Na₂CO₃, CaO, NaOH, etc.)
Metallurgy: Concentration methods, reduction processes, refining techniques
Hydrogen: Position in periodic table, isotopes, properties of H₂O₂, heavy water

Tier 3 — Occasionally Tested

f-Block: Lanthanoid/actinoid properties, lanthanoid contraction and its consequences
Noble Gases: Xenon fluorides and oxides, VSEPR shapes

For Tier 1 topics, aim to recall from memory without notes. For Tier 2, understand the pattern. For Tier 3, one quick read before the exam is enough.

Important Formulas

Inorganic Chemistry is less formula-heavy than Physical, but these are non-negotiable:

\mu = \sqrt{n(n+2)} \text{ BM}

where $n$ = number of unpaired electrons.

When to use: Any question asking about magnetic properties of d-block ions. First find the electronic configuration, count unpaired electrons, plug in. NEET 2023 asked this for Fe²⁺ — answer was $\sqrt{24}$ = 4.90 BM.

For octahedral complexes:

\text{CFSE} = (-0.4 \times n_{t_{2g}} + 0.6 \times n_{e_g}) \times \Delta_o

When to use: Comparing stability of complexes, explaining why certain configurations are preferred. Strong field ligands give larger $\Delta_o$ .

$\text{EAN} = Z - \text{oxidation state} + 2 \times \text{(number of ligands for }\sigma\text{-donors)}$

When to use: Verify coordination number in classical Werner complexes. Less tested now, but EAN = 36 (Kr), 54 (Xe) signals a stable complex.

Key reactions to know by heart:

Disproportionation of $\text{H}_2\text{O}_2$ : $2\text{H}_2\text{O}_2 \rightarrow 2\text{H}_2\text{O} + \text{O}_2$
Bleaching action of $\text{Cl}_2$ : $\text{Cl}_2 + \text{H}_2\text{O} \rightarrow \text{HCl} + \text{HOCl}$ ; HOCl releases [O]
Thermite reaction: $\text{Fe}_2\text{O}_3 + 2\text{Al} \rightarrow \text{Al}_2\text{O}_3 + 2\text{Fe}$ (aluminothermic reduction)
Chrome alum: $\text{K}_2\text{SO}_4 \cdot \text{Cr}_2(\text{SO}_4)_3 \cdot 24\text{H}_2\text{O}$ — example of double salt vs. complex

Solved Previous Year Questions

PYQ 1 — NEET 2024 (Coordination Compounds)

Question: The IUPAC name of $[\text{Pt}(\text{NH}_3)_2\text{Cl}_2]$ is:

(A) Diamminedichloroplatinum(II) (B) Dichlorodiammineplatinum(II) (C) Platinum(II) diamminedichloride (D) Diaminodichloroplatinum(2+)

Solution:

We name ligands alphabetically, anionic ligands first if they come alphabetically before neutral ones — but the rule is strictly alphabetical regardless of charge.

Ligands: $\text{Cl}^-$ (chlorido), $\text{NH}_3$ (ammine)
Alphabetical order: ammine before chlorido — so ammine comes first.
Count: di-ammine, di-chlorido
Metal: Platinum in +2 state → platinum(II)

Name: Diamminedichloridoplatinum(II)

The official IUPAC uses “chlorido” (2013 recommendations), but older NCERT uses “chloro”. NEET accepts both.

Answer: (A)

Students write “diamminedichloroplatinum(II+)” — the charge on the complex ion goes inside the bracket only when the complex is ionic. This is a neutral complex, so no charge in the name.

PYQ 2 — NEET 2023 (p-Block — Oxoacids of Sulphur)

Question: The oxidation state of sulphur in $\text{H}_2\text{S}_2\text{O}_8$ (Peroxodisulphuric acid) is:

(A) +6 (B) +7 (C) +5 (D) +8

Solution:

The key here is recognising the peroxo linkage (–O–O–). In $\text{H}_2\text{S}_2\text{O}_8$ , there is a –O–O– bridge, meaning two oxygen atoms carry a –1 oxidation state each (peroxo oxygens), while the remaining six oxygens carry the usual –2.

Setting up the equation:

2(+1) + 2x + 6(-2) + 2(-1) = 0

2 + 2x - 12 - 2 = 0

2x = 12 \Rightarrow x = +6

Sulphur is in the +6 oxidation state.

Answer: (A)

Whenever you see “peroxo” or “peroxodi” in the name, immediately account for the –O–O– bridge where each O = –1. Same logic applies to $\text{H}_2\text{S}_2\text{O}_7$ (no peroxo link, all O = –2, S = +7).

PYQ 3 — NEET 2022 (d-Block — Catalytic Properties)

Question: Which of the following transition metals does NOT show catalytic activity primarily due to its electronic configuration?

(A) Zinc (Zn) (B) Iron (Fe) (C) Nickel (Ni) (D) Vanadium (V)

Solution:

Transition metals act as catalysts because of:

Variable oxidation states (can form intermediates)
Ability to adsorb reactants on their surface (incomplete d-orbitals available)

Zinc has the configuration [Ar] $3d^{10}$ $4s^2$ . The d-orbitals are completely filled. This means Zn cannot show variable oxidation states (it’s always +2) and has very limited adsorption capacity.

Fe, Ni, V all have partially filled d-orbitals — they are classic catalysts (Fe in Haber’s process, V₂O₅ in Contact process, Ni in hydrogenation).

Answer: (A)

Difficulty Distribution

Based on NEET papers from 2019–2024:

Difficulty	% of Inorganic Questions	What This Means
Easy	40%	Direct recall — NCERT line-by-line facts
Medium	45%	Application of concepts, IUPAC naming, structure identification
Hard	15%	Multi-concept integration, less common oxoacids, unusual coordination scenarios

This 40% easy + 45% medium split means that systematic NCERT coverage gives you 85% of questions. There is no reason to touch reference books for inorganic unless you’re targeting 170+.

The hard questions typically come from:

Unusual oxidation states in polyhalides or interhalogen compounds
Isomers in coordination chemistry (ionisation, linkage, geometrical combined)
f-Block numerical (magnetic moment, lanthanoid contraction consequences)

Expert Strategy

How toppers actually approach this chapter:

Phase 1 — NCERT cover-to-cover, twice. Not skimming. Every reaction, every exception, every table. NEET setters pull exact lines from NCERT. The classic example: “Which gas is produced when bleaching powder reacts with dilute H₂SO₄?” — the answer is in one sentence of NCERT Class 12, Chapter 7.

Phase 2 — Build reaction chains. For p-block, don’t memorise reactions in isolation. Map them: Cl₂ → HCl → NaCl → bleaching powder → HOCl → Cl₂. Understanding the chain means you can reconstruct forgotten reactions.

Phase 3 — Coordination Compounds gets dedicated revision. This chapter alone gives 2–3 questions. Learn the 15 most common ligands (names + charges), master IUPAC naming, and know the spectrochemical series cold: I⁻ < Br⁻ < Cl⁻ < F⁻ < OH⁻ < H₂O < NH₃ < en < CN⁻ < CO.

For revision week before NEET: spend 30 minutes on inorganic daily — just flashcards of exceptions, anomalies, and IUPAC names. This chapter rewards recency of revision more than any other.

Phase 4 — PYQs by chapter. Solve last 10 years’ NEET inorganic questions chapter-wise (not year-wise). You’ll notice that the same concepts repeat in slightly different wrappers. After 3–4 PYQ sets, you’ll start predicting the “type” of question before finishing reading it.

Time allocation in the exam: Inorganic questions should take 45–60 seconds each. If a question is taking longer than 90 seconds, mark and move. Come back with fresh eyes — sometimes a second read resolves it instantly.

Common Traps

Trap 1 — Diagonal Relationship Confusion. Students mix up Li–Mg and Be–Al diagonals. Li resembles Mg (both form normal oxides, both have high charge density cations). Be resembles Al (both form amphoteric oxides, both form covalent halides). The trap question: “Which alkali metal forms a peroxide on burning in excess oxygen?” — answer is Na, not Li (Li forms the normal oxide Li₂O).

Trap 2 — Ionisation Enthalpy Anomaly. The expected order is: IE₁ of N < O and IE₁ of Be < B — but the actual order reverses both. N has a half-filled p-subshell (extra stability), so IE₁(N) > IE₁(O). Be has a filled 2s subshell, so IE₁(Be) > IE₁(B). NEET uses this in almost every alternate year. If you see IE₁ values and they seem “wrong”, check if you’re applying this rule.

Trap 3 — Colour of Coordination Compounds. Students assume all d¹⁰ complexes are colourless. That’s true for isolated metal ions, but $[\text{Cu}(\text{NH}_3)_4]^{2+}$ is deep blue even though Cu²⁺ has a d⁹ configuration (not d¹⁰). The trap: $\text{Zn}^{2+}$ complexes are colourless (d¹⁰), $\text{Cu}^+$ complexes are colourless (d¹⁰), but $\text{Cu}^{2+}$ complexes are coloured (d⁹). Don’t confuse Cu⁺ and Cu²⁺.

Trap 4 — Froth Flotation vs. Leaching. Froth flotation is for sulphide ores (ZnS, Cu₂S, PbS). Leaching (chemical dissolution) is for oxide and carbonate ores. NEET sometimes asks about bauxite — this uses leaching (with NaOH), not froth flotation. Students who memorise “ore → froth flotation” as a reflex lose this mark.

Trap 5 — Hybridisation vs. Shape in XeF₄. XeF₄ is sp³d² hybridised (octahedral electron geometry) but square planar in shape. The two lone pairs occupy axial positions. NEET often asks about “shape” — always distinguish between electron geometry (includes lone pairs) and molecular geometry (only bond pairs count for shape).

One final pattern to watch: NEET frequently gives a statement about a property and asks “which of the following is/are correct?” For inorganic, these are usually testing exceptions and anomalies. Train yourself to immediately think: Is there an exception to the general trend being stated here? That question alone will save you 4–8 marks.