Chemistry UPSC PYQ — Elements, Compounds & Reactions

In India, the use of carbofuran, methyl parathion, phorate and triazophos is viewed with apprehension. These chemicals are used as

1. A pesticides in agriculture
2. B preservatives in processed foods
3. C fruit-ripening agents
4. D moisturising agents in cosmetics

Chlorination is a process used for water purification. The disinfecting action of chlorine is mainly due to

1. A The formation of hydrochloric acid when chlorine is added to water
2. B The formation of hypochlorous acid when chlorine is added to water
3. C The formation of nascent oxygen when chlorine is added to water
4. D The formation of hydrogen when chlorine is added to water

Which one of the following is used as an explosive ?

1. A Phosphorus trichloride
2. B Mercuric oxide
3. C Graphite
4. D Nitroglycerine

What is Bisphenol A (BPA)?

1. A A medical test for detecting cancer
2. B A test for testing the use of drugs to improve performance by athletes
3. C A chemical used for the development of food-packaging materials
4. D A special type of alloy steel

What is Agent Orange?

1. A An ace spying group trained by the Police in London
2. B A weed-killing chemical used by the US Military in the Vietnam War
3. C A technique used in the advanced railway safety procedure
4. D A special chemical used in making alloy steel

Which one of the following is also called Stranger Gas?

1. A Argon
2. B Neon
3. C Xenon
4. D Nitrous oxide

Which one of the following is another name of RDX?

1. A Cyanohydrin
2. B Dextran
3. C Cyclohexane
4. D Cyclonite

Consider the following chemicals: 1. Benzene 2. Carbon tetrachloride 3. Sodium carbonate 4. Trichloroethylene Which of the above is/are used as dry-cleaning chemicals?

1. A 1 only
2. B 2 only
3. C 1, 2 and 4 only
4. D 1, 2, 3 and 4

Salts of which of the following elements provide colours to fireworks?

1. A Zinc and sulphur
2. B Potassium and mercury
3. C Strontium and barium
4. D Chromium and nickel

Which one of the following statements is correct?

1. A Liquid sodium is employed as a coolant in nuclear reactors
2. B Calcium carbonate is an ingredient of toothpaste
3. C Bordeaux mixture consists of sodium sulphate and lime
4. D Zinc amalgams are used as a dental filling

Consider the following statements The purpose of adding sodium sulphate and sodium silicate to the detergent in a washing powder is 1. To keep the washing powder dry 2. To maintain the alkalinity of the powder Which of these statements is/are correct?

1. A Only 1
2. B Only 2
3. C Both 1 and 2
4. D Neither 1 nor 2

Which one of the following statements is correct?

1. A The presence of NaCl increases the rate of setting of Plaster of Paris
2. B Gypsum is added to the cement to slow down its rate of setting
3. C All alkaline earth metals form hydrated salts
4. D Barium and Strontium are found free in nature

Which one of the following statements is correct?

1. A The boiling point of an aqueous solution is higher than that of pure water
2. B Addition of solutes to a solution causes an increase in its water potential
3. C The vapour pressure of the water in a solution is lower than that of pure water
4. D When a solution is separated from water by a semi permeable membrane, water movement can be prevented by applying pressure to the solution

Match List I (Industrial processes) with List II (Industry with which associated) and select the correct answer using the codes given below the Lists: List I I. Cracking II. Smelting III. Hydrogenation IV. Vulcanization List II A) Rubber B) Petroleum C) Copper D) Edible fats Codes:

1. A I-C, II-B, III-A, IV-D
2. B I-B, II-C, III-D, IV-A
3. C I-B, II-C, III-A, IV-D
4. D I-C, II-B, III-D, IV-A

Which one of the following was used as a chemical weapon in the First World War?

1. A Carbon monoxide
2. B Hydrogen cyanide
3. C Mustard gas
4. D Water gas

Which one of the following is a mixed fertilizer?

1. A CAM
2. B Urea
3. C Ammonium Sulphate
4. D NPK

The chemical used as a ‘fixer’ in photography is

1. A sodium sulphate
2. B sodium thiosulphate
3. C ammonium persulphate
4. D borax

Consider the following statements : 1. Anhydrous sodium carbonate is commonly known as baking soda 2. Baking soda is used in fire extinguishers 3. Bleaching powder is manufactured in Hasenclever plant Which of the statements given above is/are correct?

1. A 1, 2 and 3
2. B 2 and 3
3. C 3 only
4. D 1 and 2

Consider the following statements: 1. Banking soda is used in fire extinguishers. 2. Quicklime is used in the manufacture of glass. 3. Gypsum is used in the manufacture of Plaster of Paris. Which of the statements given above is/are correct?

1. A 1 and 2
2. B 2 and 3
3. C 1 only
4. D 1, 2 and 3

Assertion (A): Synthetic detergents can lather well in hard water. Reason (R): Synthetic detergents form soluble calcium and magnesium salts with hard water.

1. A Both A and R are individually true and R is the correct explanation of A
2. B Both A and R are individually true but R is not a correct explanation of A
3. C A is true but R is false
4. D A is false but R is true

An aqueous solution of copper sulphate is acidic in nature because the salt undergoes

1. A dialysis
2. B electrolysis
3. C hydrolysis
4. D photolysis

Match List I with List II and select the correct answer using the codes given below the Lists: List I I. German Silver II. Solder III. Bleaching Powder IV. Hypo List II A) Tin B) Nickel C) Sodium D) Chlorine Codes:

1. A I-A, II-B, III-D, IV-C
2. B I-B, II-A, III-C, IV-D
3. C I-A, II-B, III-C, IV-D
4. D I-B, II-A, III-D, IV-C

Consider the following statements: Hard water is not suitable for I. Drinking. II. Washing clothes with soap. III. Use in boilers. IV. Irrigating crops. Which of these statements are correct?

1. A I and III
2. B II and III
3. C I, II and IV
4. D I, II, III and IV

Assertion (A): To dilute sulphuric acid, acid is added to water and not water to acid. Reason (R): Specific heat of water is quite large.

1. A Both A and R are true, and R is the correct explanation of A
2. B Both A and R are true, but R is not a correct explanation of A
3. C A is true, but R is false
4. D A is false, but R is true

Match List I with List II and select the correct answer using the codes given below the lists: List I I. Potassium bromide II. Potassium nitrate III. Potassium sulphate IV. Mono-potassium tartrate List II A. Fertiliser B. Photography C. Bakery D. Gunpowder Codes:

1. A I-B, II-D, III-A, IV-C
2. B I-B, II-D, III-C, IV-A
3. C I-D, II-B, III-C, IV-A
4. D I-D, II-B, III-A, IV-C

Which one of the following metals does not form amalgams?

1. A Zinc
2. B Copper
3. C Magnesium
4. D Iron

Match List I with List II and select the correct answer using the codes given below the lists: List I I. Blue vitriol II. Epsom salt III. Baking soda IV. Caustic soda List II A) Sodium bicarbonate B) Sodium hydroxide C) Magnesium sulphate D) Copper sulphate

1. A I-C, II-D, III-B, IV-A
2. B I-D, II-C, III-A, IV-B
3. C I-C, II-D, III-A, IV-B
4. D I-D, II-A, III-B, IV-A

Assertion (A): Sodium metal is stored under kerosene. Reason (R): Metallic sodium melts when exposed to air.

1. A Both A and R are true, and R is the correct explanation of A
2. B Both A and R are true, but R is NOT a correct explanation of A
3. C A is true, but R is false
4. D A is false, but R is true

Which one of the following pairs of metals constitutes the lightest metal and the heaviest metal, respectively?

1. A Lithium and mercury
2. B Lithium and osmium
3. C Aluminium and osmium
4. D Aluminium and mercury

Which one of the following non-metals is NOT a poor conductor of electricity?

1. A Sulphur
2. B Selenium
3. C Bromide
4. D Phosphorus

Assertion (A): In the periodic table of chemical elements, electron affinity is always found to increase from top to bottom in a group. Reason (R): In a group, the atomic radius generally increases from top to bottom.

1. A Both A and R are individually true and R is the correct explanation of A
2. B Both A and R are individually true but R is NOT the correct explanation of A
3. C A is true but R is false
4. D A is false but R is true

Which one of the following is NOT radioactive?

1. A Astatine
2. B Francium
3. C Tritium
4. D Zirconium

In an atom, the order of filling up of the orbitals is governed by

1. A Aufbau principle
2. B Heisenberg’s uncertainty principle
3. C Hund’s rule
4. D Pauli’s exclusion principle

Consider the following statements with reference to the Periodic Table of chemical elements: I. Ionisation potential gradually decreases along a period. II. In a group of elements, electron affinity decreases as the atomic weight increases. III. In a given period, electronegativity decreases as the atomic number increases. Which of these statement(s) is/are correct?

1. A I only
2. B II only
3. C I and III
4. D II and III

Which one of the following is present in the largest amount in terms of per cent by mass in the earth’s crust?

1. A Silicon
2. B Oxygen
3. C Carbon
4. D Calcium

The most reactive among the halogens is

1. A fluorine
2. B chlorine
3. C bromine
4. D iodine

Which one of the following is paramagnetic in nature?

1. A Iron
2. B Hydrogen
3. C Oxygen
4. D Nitrogen

Assertion (A): Unsaturated fats are more reactive compared with the saturated fats. Reason (R): Unsaturated fats have only single bonds in their structure.

1. A Both A and R are individually true and R is the correct explanation of A
2. B Both A and R are individually true but R is NOT the correct explanation of A
3. C A is true but R is false
4. D A is false but R is true

Which one of the following is the correct sequence in increasing order of molecular weights of the hydrocarbons?

1. A Methane, ethane, propane and butane
2. B Propane, butane, ethane and methane
3. C Butane, ethane, propane and methane
4. D Butane, propane, ethane and methane

Consider the following statements about acetylene: I. It is used in welding industry. II. It is raw material for preparing plastics. III. It is easily obtained by mixing silicon carbide and water. Of these statements:

1. A I and II are correct
2. B I and III are correct
3. C II and III are correct
4. D I, II and III are correct

Assertion (A): Formic acid is a stronger acid than acetic acid. Reason (R): Formic acid is an organic acid.

1. A Both A and R are true, and R is the correct explanation of A
2. B Both A and R are true, but R is NOT a correct explanation of A
3. C A is true, but R is false
4. D A is false, but R is true

Assertion (A): Phenyl is used as a household germicide. Reason (R): Phenyl is a phenol derivative and phenol is an effective germicide.

1. A Both A and R are true, and R is the correct explanation of A
2. B Both A and R are true, but R is NOT a correct explanation of A
3. C A is true, but R is false
4. D A is false, but R is true

The characteristic odour of garlic is due to

1. A a chloro compound
2. B a sulphur compound
3. C a fluorine compound
4. D acetic acid

Which one of the following is an active component of oil of clove?

1. A Menthol
2. B Eugenol
3. C Methanol
4. D Benzaldehyde

Which one of the following is used as an anti-freeze for the automobile engines?

1. A Propyl alcohol
2. B Ethanol
3. C Methanol
4. D Ethylene glycol

Which of the following is/are the example/examples of chemical change? 1. Crystallization of sodium chloride 2. Melting of ice 3. Souring of milk Select the correct answer using the code given below.

1. A 1 and 2 only
2. B 3 only
3. C 1, 2 and 3
4. D None

With reference to ionic compounds, consider the following statements: 1. Ionic compounds are insoluble in alcohol. 2. Ionic compounds in the solid state are good conductors of electricity. Which of these statements is/are correct?

1. A Only 1
2. B Only 2
3. C Both 1 and 2
4. D Neither 1 nor 2

Match List I (Oxidation number) with List II (The element) and select the correct answer using the codes given below the lists: List I (Oxidation number) — List II (The element) A. 2 — 1. Oxidation number of Mn in MnO₂ B. 3 — 2. Oxidation number of S in H₂S₂O₇ C. 4 — 3. Oxidation number of Ca in CaO₂ D. 6 — 4. Oxidation number of Al in NaAlH₄

1. A A-3, B-4, C-1, D-2
2. B A-4, B-3, C-1, D-2
3. C A-3, B-4, C-2, D-1
4. D A-4, B-3, C-2, D-1

Assertion (A): With the increase of temperature, the viscosity of glycerine increases. Reason (R): Rise of temperature increases kinetic energy of molecules.

1. A Both A and R are individually true and R is the correct explanation of A
2. B Both A and R are individually true but R is not a correct explanation of A
3. C A is true but R is false
4. D A is false but R is true

Assertion (A): A chemical reaction becomes faster at higher temperatures. Reason (R): At higher temperatures, molecular motion becomes more rapid. Which of the following is correct?

1. A Both A and R are individually true and R is the correct explanation of A
2. B Both A and R are individually true but R is NOT a correct explanation of A
3. C A is true but R is false
4. D A is false but R is true

Water can dissolve more substances than any other liquid because

1. A it is dipolar in nature
2. B it is a good conductor of heat
3. C it has high value of specific heat
4. D it is an oxide of hydrogen

Who among the following discovered heavy water?

1. A Heinrich Hertz
2. B H. C. Urey
3. C G. Mendel
4. D Joseph Priestley

Which one of the following is called Philosopher’s wool?

1. A Zinc Bromide
2. B Zinc Nitrate
3. C Zinc Oxide
4. D Zinc Chloride

Which one of the following does not contain silver?

1. A Horn Silver
2. B German Silver
3. C Ruby Silver
4. D Lunar Caustic

A small pouch containing silica gel is often found in bottles of medicine in tablet or powder form because silica gel

1. A kills bacteria
2. B kills germs and spores
3. C absorbs moisture
4. D absorbs all gases present inside the bottle