NDA General Studies · Chemistry · 30 questions · 2017 to 2026
NDA Chemistry in everyday life previous year questions with solutions
Chemistry in everyday life is about one General Studies question in forty, two or three a sitting, and rising since 2023, with paints and cement leading. The questions are one-fact recall, with pairs and statement sets since 2026. Every question UPSC has set on it since 2017, solved. Grouped by the method each needs, newest first; open a question for its answer and worked solution.
13.1 Soaps and detergents: saponification, micelles and hard water (7)13.2 Fertilisers: nitrogenous, phosphatic and potassic (5)13.3 Glass, cement and silica: raw materials, composition and setting (8)13.4 Paints, pigments and paper (6)13.5 Drugs, food chemicals and chemicals in daily use; a box on explosives (4)
13.1 Soaps and detergents: saponification, micelles and hard water
1. NDA 2026 (II)
Coconut oil upon hydrolysis with potassium hydroxide gives:
Answer and solution
Answer: (d) Glycerol and potassium salts of fatty acids
Method. Saponification of oil with KOH
A triglyceride (coconut oil) + 3KOH -> glycerol + 3 RCOOK (potassium soap). Glycerol (not glycol) and potassium (not sodium) salts. Standard result; NCERT Class 10 ch 4 and Class 12 Chemistry in Everyday Life.
2. NDA 2025 (I)
Which one of the following statements is NOT correct?
Answer and solution
Answer: (d) In micelles the ionic-end of the molecules is towards oil droplet while the other end faces outside
Method. Soap micelles (negative)
Soaps are Na/K salts of long-chain fatty acids with a hydrophobic tail and hydrophilic ionic head (a, b true). Detergents do not form scum with hard-water ions so they work better (c true). In a micelle the hydrophobic tails point inward toward the oil droplet and the ionic heads face the water outside, so (d) is reversed and incorrect. NCERT Class 10 ch 4; standard result.
3. NDA 2024 (I)
Soap with water forms:
Answer and solution
Answer: (d) Lyotropic liquid crystal
Method. Soap in water
Soap molecules in water above a critical concentration form micelles and ordered lamellar phases; such phases formed by a solvent plus an amphiphile are lyotropic liquid crystals. Thermotropic phases depend on temperature of a pure compound. 'Metallotropic' is a different class (metal-containing). Standard result.
4. NDA 2023 (I)
What is the specific purpose of using potassium hydroxide during the saponification process?
Answer and solution
Answer: (b) To obtain soaps which are soft on the skin
Method. Saponification with KOH
Fat + NaOH gives hard sodium soap; fat + KOH gives potassium soap, which is soft and used for toilet soft soaps, shaving soaps. KOH is costlier, so (d) is wrong. NCERT Class 10 ch 4; standard result.
5. NDA 2021 (I)
Which one of the following statements about the cleansing action of soap is not true?
Answer and solution
Answer: (c) Soaps are ammonium salts of long chain carboxylic acids.
Method. Cleansing action of soap (negative)
Soaps are sodium or potassium salts of long-chain fatty acids, not ammonium salts, so (c) is false. (a) the hydrophobic tails trap oil in the micelle centre, (b) colloidal micelles scatter light (Tyndall effect), (d) Ca2+ and Mg2+ give insoluble scum: all true. NCERT Class 10 ch 4 (soaps and detergents); standard result.
6. NDA 2019 (II)
A sample of ‘soft soap’ contains
Answer and solution
Answer: (b) Potassium
Method. Soft soap
Soaps made with KOH are potassium salts of fatty acids; they are soft (soft soap, shaving cream). Sodium soaps are hard. Calcium and magnesium salts are insoluble scum. NCERT Class 10 ch 4 and Class 12 Chemistry in Everyday Life; standard result.
7. NDA 2019 (I)
Which one of the following is NOT a synthetic detergent?
Answer and solution
Answer: (c) CH3(CH2)16COO- Na+
Method. Soap versus synthetic detergent
(a) sodium lauryl sulphate is an anionic detergent; (b) cetyltrimethylammonium bromide is a cationic detergent; (d) a stearic ester of polyethylene glycol is a non-ionic detergent. (c) sodium stearate is ordinary soap, a carboxylate salt, so it is not a synthetic detergent. NCERT Class 12 Chemistry in Everyday Life (pre-2023), detergent classes; standard result.
13.2 Fertilisers: nitrogenous, phosphatic and potassic
8. NDA 2026 (I)
Superphosphate of lime—a phosphate fertilizer—is obtained by the reaction of
Answer and solution
Answer: (b) calcium phosphate with sulphuric acid
Method. Superphosphate of lime
Ca3(PO4)2 + 2H2SO4 -> Ca(H2PO4)2 + 2CaSO4. The acid converts insoluble calcium phosphate to soluble monocalcium phosphate (superphosphate). Standard result.
9. NDA 2026 (I)
Which of the following statements is/are correct with regard to Nitrolim?
I. It is prepared by heating calcium carbide with nitrogen.
II. It decomposes into ammonia in soil.
III. It is an NPK fertilizer.
IV. It is an organic fertilizer.
Select the answer using the code given below.
I. It is prepared by heating calcium carbide with nitrogen.
II. It decomposes into ammonia in soil.
III. It is an NPK fertilizer.
IV. It is an organic fertilizer.
Select the answer using the code given below.
Answer and solution
Answer: (a) I and II only
Method. Nitrolim (calcium cyanamide)
I true: CaC2 + N2 -> CaCN2 + C on heating. II true: CaCN2 + 3H2O -> CaCO3 + 2NH3 in soil. III false: it supplies only N (and Ca), not an NPK mix. IV false: it is an inorganic fertiliser. So I and II only. Standard result.
10. NDA 2024 (II)
Which one among the following fertilizers is a source of nitrogen?
Answer and solution
Answer: (d) Urea
Method. Nitrogen fertiliser
Urea (46% N) is a nitrogen fertiliser. Superphosphate and bone meal supply phosphorus; potassium sulfate supplies potassium. Standard result.
11. NDA 2022 (I)
Which one of the following statements about fertilizers is not correct?
Answer and solution
Answer: (a) Urea is a phosphorus-containing fertilizer.
Method. Fertilisers (negative)
Urea, CO(NH2)2, is a nitrogen fertiliser (about 46% N, the highest of the solid fertilisers), made from NH3 and CO2 at high pressure and temperature (c, d true; b true as loosely worded: fertiliser replenishes nutrients). Urea contains no phosphorus, so (a) is the incorrect statement. Standard result.
12. NDA 2018 (II)
Which one of the following is not used as fertilizer?
Answer and solution
Answer: (b) Ammonium sulphide
Method. Identify the non-fertiliser
Ammonium nitrate, phosphate and sulphate all supply N (and P) and are standard fertilisers. Ammonium sulphide is a toxic, foul-smelling reagent salt, not used as a fertiliser. Standard result (industrial chemistry of fertilisers).
13.3 Glass, cement and silica: raw materials, composition and setting
13. NDA 2026 (II)
Which of the following statements is/are correct in respect of Portland cement?
I. Adding more water (higher water-cement ratio) accelerates the initial setting time of cement.
II. The addition of a small percentage of gypsum gives the desired retardation.
III. Gypsum is added during manufacturing to accelerate the setting time of cement.
Select the answer using the code given below:
I. Adding more water (higher water-cement ratio) accelerates the initial setting time of cement.
II. The addition of a small percentage of gypsum gives the desired retardation.
III. Gypsum is added during manufacturing to accelerate the setting time of cement.
Select the answer using the code given below:
Answer and solution
Answer: (d) II only
Method. Setting of Portland cement
Clinker alone sets flash-fast through tricalcium aluminate; a few percent of gypsum is ground in to retard setting, so II is true and III false. I is false: a higher water-cement ratio delays setting and hardening and lowers strength rather than accelerating it. Only II is correct. Standard result.
14. NDA 2025 (II)
Which one of the following is NOT present in cement?
Answer and solution
Answer: (c) 4CaO·SiO2
Method. Compounds of Portland cement (negative)
The Bogue compounds are tricalcium silicate 3CaO.SiO2, dicalcium silicate 2CaO.SiO2, tricalcium aluminate 3CaO.Al2O3 and tetracalcium aluminoferrite 4CaO.Al2O3.Fe2O3. 4CaO.SiO2 is not a cement compound (the silicates are only 3:1 and 2:1), so it is the one not present. Standard result.
15. NDA 2024 (I)
Which among the following are essential constituents of Portland cement?
Answer and solution
Answer: (b) Silica, alumina, lime
Method. Constituents of Portland cement
The essential oxides are lime (CaO), silica (SiO2) and alumina (Al2O3), with some iron oxide. Option (a) sand, lime, clay lists raw materials rather than the oxide constituents; graphite and graphene are irrelevant. Answered b. Standard result.
16. NDA 2023 (I)
For manufacturing of glass, which among the following is used as a source of silica?
Answer and solution
Answer: (d) Sand
Method. Silica source for glass
Glass is made by fusing sand (SiO2) with soda ash and limestone. Clay, wood powder and coconut shell are not the silica source for glass. Standard result.
17. NDA 2021 (I)
Which one of the following is not used as a raw material in the manufacture of glass?
Answer and solution
Answer: (d) Gypsum
Method. Glass raw materials (negative)
Glass is made from sand (silica) with soda ash (soda), limestone/lime, and additives: alumina for toughness, borax for borosilicate glass. Gypsum (CaSO4.2H2O) is not a glass raw material (it is added to cement). Standard result.
18. NDA 2020 (I)
Which one of the following is the best example of desiccant?
Answer and solution
Answer: (a) Silica gel
Method. Desiccant
A desiccant is a drying agent that adsorbs moisture. Silica gel is the standard example (packed in boxes). Polystyrene is a plastic; NaCl and Na2CO3 are not used as desiccants (anhydrous Na2CO3 is a weak one, but silica gel is the best). Standard result.
19. NDA 2019 (II)
Which one of the following statements about glass is not correct?
Answer and solution
Answer: (c) Soda glass is harder than pyrex glass.
Method. Properties of glass
Glass is an amorphous supercooled liquid with no sharp melting point (a, b true); pyrex is borosilicate with B2O3 (d true). Pyrex is the harder, more heat-resistant glass; soda glass is softer and melts at a lower temperature, so (c) is false. Standard result.
20. NDA 2019 (II)
The raw materials used for the manufacture of Portland cement are
Answer and solution
Answer: (c) Lime, silica and alumina
Method. Raw materials of Portland cement
Cement is made by heating limestone (lime source) with clay/shale (silica and alumina) plus a little iron oxide, then adding gypsum. Lime, silica and alumina is the set. SO2, CO2 (a gas product) and boric acid are not raw materials. Standard result.
13.4 Paints, pigments and paper
21. NDA 2026 (I)
Consider the following pairs:
I. Pigment: TiO2
II. Drier: Turpentine
III. Thinner: Naphthenates
IV. Antiskinning agent: Polyhydroxy phenol
How many of the pairs given above are correctly matched?
I. Pigment: TiO2
II. Drier: Turpentine
III. Thinner: Naphthenates
IV. Antiskinning agent: Polyhydroxy phenol
How many of the pairs given above are correctly matched?
Answer and solution
Answer: (b) Two
Method. Paint components
I correct: TiO2 is a white pigment. II wrong: turpentine is a thinner; naphthenates (and linoleates) of Co, Mn, Pb are driers. III wrong: the roles are swapped. IV correct: polyhydroxy phenol is an anti-skinning agent. Two pairs correct. Standard result (paint chemistry).
22. NDA 2026 (I)
Consider the following statements:
I. Pine oil is used as antifoaming agent in the emulsion paints.
II. Protective colloids are used in the emulsion paints to decrease their stability.
III. Driers having oxidizable oils are added to the emulsion paints to accelerate drying process.
Which of the statements given above is/are correct?
I. Pine oil is used as antifoaming agent in the emulsion paints.
II. Protective colloids are used in the emulsion paints to decrease their stability.
III. Driers having oxidizable oils are added to the emulsion paints to accelerate drying process.
Which of the statements given above is/are correct?
Answer and solution
Answer: (d) I and III
Method. Emulsion paints
I true: pine oil (and octyl alcohol) is the anti-foaming agent of emulsion paints. II false: protective colloids such as casein, gelatin and methyl cellulose are added to increase the stability of the emulsion, not to decrease it. III true: an emulsion paint whose film-former is an oxidisable oil or alkyd needs driers (cobalt or manganese naphthenates) to accelerate drying; only a pure latex (PVA, acrylic) dries by evaporation and coalescence alone. I and III are correct: (d). Standard result (paint chemistry).
23. NDA 2026 (I)
Which of the following is/are the physical test(s) employed for the manufacture of paper?
I. Mechanical and strength properties
II. Surface properties
III. Optical properties
IV. Permeability to fluids
Select the correct answer using the code given below.
I. Mechanical and strength properties
II. Surface properties
III. Optical properties
IV. Permeability to fluids
Select the correct answer using the code given below.
Answer and solution
Answer: (d) I, II, III and IV
Method. Physical tests of paper
Paper testing covers mechanical and strength properties (burst, tear, tensile), surface properties (smoothness), optical properties (brightness, opacity) and permeability to fluids (porosity, water absorption). All four are physical tests. Standard result.
24. NDA 2024 (II)
Which one among the following is commonly used as an ‘anti-skinning agent’ in paints?
Answer and solution
Answer: (d) Polyhydroxy phenol
Method. Anti-skinning agent
An anti-skinning agent prevents surface skin formation in oil paints by acting as an antioxidant that delays oxidation of the surface. Polyhydroxy phenols (for example catechol-type compounds, also methyl ethyl ketoxime) are the standard type. Gelatin, NMP and pyridine are not. Standard result (paint chemistry).
25. NDA 2022 (I)
Which one of the following is not a pigment?
Answer and solution
Answer: (d) Silica
Method. Pigments versus fillers (negative)
Zinc oxide (zinc white) and white lead are white pigments. Chalk (whiting, CaCO3) is classed as a white extender pigment. Silica is an inert filler/extender with no colour or opacity of its own, so it is the best answer for 'not a pigment'. Standard result (paint chemistry).
26. NDA 2019 (I)
Which one of the following is used as a binder in paints?
Answer and solution
Answer: (b) Novolac
Method. Binder (film-former) in paints
Pigments give colour: TiO2 (white) and phthalocyanine (blue/green) are pigments, so a and c are out. The binder is the resin that forms the film. Of b and d, novolac (phenol-formaldehyde, the bakelite resin) is the standard phenolic paint binder; silicone resins also bind (heat-resistant paints), so the item is loosely framed. Answered b by the standard reading of phenolic resin as binder. Standard result (paint chemistry).
13.5 Drugs, food chemicals and chemicals in daily use; a box on explosives
27. NDA 2025 (II)
Which one of the following type of medicines is used for treating indigestion?
Answer and solution
Answer: (d) Antacid
Method. Antacids
Indigestion and acidity are relieved by antacids such as milk of magnesia and sodium bicarbonate, which neutralise excess stomach acid. Analgesics relieve pain, antiseptics kill germs on tissue and antibiotics act on bacteria. NCERT Class 12 Chemistry in Everyday Life (pre-2023); standard result.
28. NDA 2023 (I)
Browning of the chopped apple can be minimized by:
Answer and solution
Answer: (c) using lemon juice.
Method. Enzymatic browning
Browning is the polyphenol oxidase enzyme oxidising phenols using O2. Lemon juice supplies citric and ascorbic acid, which lowers the pH and is an antioxidant, so it slows browning. Sugar, a container and the basic milk of magnesia do not stop it (base would raise pH). Standard food chemistry.
29. NDA 2023 (I)
Airbags work on the principle of a chemical reaction triggered by the impact producing a gaseous product that causes a sudden volume change. Which one among the following chemical conversions is responsible for this?
Answer and solution
Answer: (a) Sodium azide into nitrogen gas
Method. Airbag chemistry
On impact, sodium azide decomposes: 2NaN3 -> 2Na + 3N2, and the nitrogen gas inflates the bag in milliseconds (the sodium is then removed with KNO3 and SiO2). Options with CO2 are not used. Standard result.
30. NDA 2021 (II)
Which one of the following compounds is used in ‘black and white’ photography?
Answer and solution
Answer: (b) AgBr
Method. Photographic emulsion
Black and white film uses a gelatin emulsion of silver bromide (AgBr), which is light-sensitive and reduced to silver on developing; AgBr is also fixed with hypo. AgF is soluble and not photosensitive; AgCl is used for printing paper but AgBr is the film compound. Standard result.
← Carbon, organic chemistry, polymers and fuelsCell, cell division and tissues →