PYQ Vault

Playbook

Industrial and Applied Chemistry

28 q · 11% HARD. Industrial gases (water gas, producer gas, syngas), cement + glass composition, fertilisers (NPK), alloys (brass, bronze, solder, stainless steel), and paints + coatings (4 q · 75% HARD — the bank's most concentrated HARD pool, pigment/drier/thinner/anti-skinning).

questions in the bank
28
tagged HARD
11%
subtopic(s)
5
worked examples
2

When you’ll see it

An industrial-gas identification (water gas / producer gas / syngas), a cement/glass composition question, an NPK fertiliser name, an alloy composition match, or a paints + coatings additive role (pigment / drier / thinner / anti-skinning).

How this chapter is tested

28 q in 10 years · 11% HARD overall — but the HARD pool concentrates almost entirely in the Paints and Coatings subtopic (3 of 4 paint q are HARD = 75%). The rest of the chapter (Industrial gases, Cement/Glass, Fertilisers, Alloys) is straight recall, mostly EASY.

Industrial Gases (8 q): water gas = CO + H₂ (from steam over hot coke); producer gas = CO + N₂ (from air over coke); syngas = CO + H₂ from natural-gas reforming. Cement (Portland) = CaO + SiO₂ + Al₂O₃ + Fe₂O₃ + MgO. Glass = SiO₂ + Na₂CO₃ + CaCO₃ (soda-lime); coloured glass adds metal oxides (Fe → green, Co → blue, Cr → green, Mn → purple).

Paints and Coatings (4 q at 75% HARD) carries a specialised vocabulary: pigment (provides colour, e.g. TiO₂ white, PbO red); vehicle/binder (linseed oil); drier (catalyst speeds drying, e.g. naphthenates); thinner (reduces viscosity, e.g. turpentine); anti-skinning agent (prevents skin formation in tin, e.g. polyhydroxy phenol). The trap is mixing up roles — TiO₂ as drier (it's a pigment), turpentine as anti-skinning (it's a thinner).

The sub-skills

The rules and habits that decide whether you get a question right.

  • Industrial gas identification

    Water gas (CO + H₂) — fuel + synthesis. Producer gas (CO + N₂) — diluted, lower CV. Syngas (CO + H₂) — same as water gas from natural gas. Coal gas (H₂ + CH₄ + CO) — town gas, distillation of coal. LPG (propane + butane) — domestic fuel.

  • Cement + glass composition

    Portland cement: CaO (~64%), SiO₂ (~22%), Al₂O₃ (~6%), Fe₂O₃ (~3%), MgO (~2%). Soda-lime glass: SiO₂ + Na₂CO₃ + CaCO₃. Pyrex (borosilicate): SiO₂ + B₂O₃ (thermal-shock resistant). Lead crystal: SiO₂ + PbO (high refractive index).

  • NPK fertiliser breakdown

    N (nitrogen): urea CO(NH₂)₂, ammonium nitrate NH₄NO₃, ammonium sulphate (NH₄)₂SO₄. P (phosphorus): superphosphate of lime (Ca(H₂PO₄)₂ + CaSO₄), triple superphosphate. K (potassium): KCl, K₂SO₄. Mixed NPK fertilisers carry all three.

  • Alloy composition recall

    Brass = Cu + Zn (60/40 to 70/30). Bronze = Cu + Sn. Stainless steel = Fe + Cr (10–18%) + Ni (8–10%) ± C. Solder = Pb + Sn (60/40). Duralumin = Al + Cu + Mg + Mn (light, aircraft). Steel = Fe + C (<2%). Wrought iron = nearly pure Fe.

  • Paint additive roles

    Pigment = colour (TiO₂ white, PbO red, Cr₂O₃ green). Vehicle/binder = film-former (linseed oil, alkyd resin). Drier = oxidation catalyst (cobalt/manganese naphthenates). Thinner = viscosity reducer (turpentine, white spirit). Anti-skinning = prevents tin skin (polyhydroxy phenol). Filler = extends pigment (CaCO₃, talc).

2 worked examples from the bank

Real past-year questions illustrating the playbook. Click to reveal options + solution.

NDA · Apr 2026 · Q85Hard

Example 1 · Industrial and Applied Chemistry · Paints and Coatings

Consider the following pairs: I. Pigment : TiO2\text{TiO}_2 II. Drier : Turpentine III. Thinner : Naphthenates IV. Antiskinning agent : Polyhydroxy phenol How many pairs are correctly matched?
NDA · Apr 2026 · Q89Moderate

Example 2 · Industrial and Applied Chemistry · Industrial Gases, Manufacturing and Reactions

Which of the following is/are physical test(s) employed for manufacture of paper? I. Mechanical and strength properties II. Surface properties III. Optical properties IV. Permeability to fluids

Traps to expect

Distractor shapes specific to this chapter. The page-wide Traps section covers the bank-level patterns.

  • Pigment vs drier role swap

    TiO₂ is a pigment (provides white colour), NOT a drier. Naphthenates are driers, NOT thinners. Turpentine is a thinner, NOT an anti-skinning agent. The HARD pair-match questions deliberately swap one role to test exact recall.

  • Stainless steel without chromium

    Stainless steel REQUIRES chromium (≥ 10.5%) — the Cr₂O₃ passive layer is what makes it 'stainless.' Some HARD questions list 'which is NOT essential in stainless steel' with Cr in the option set as a trap.

  • Glass as 'crystalline solid'

    Glass is an AMORPHOUS solid (supercooled liquid), not crystalline. The trap option treats it as crystalline because we see 'glass' as solid-looking. Crystalline = ordered lattice (e.g. NaCl, quartz); amorphous = no long-range order (glass, plastic, rubber).

Drill every industrial and applied chemistry question

28 questions from the bank, scoped to 5 bundled subtopics.

Drill the 28 questions

Related playbooks

Often paired with this one — drill these next if you found the worked examples above tractable.