HCS Exam MCQ Series: Chemistry-I
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HCS Exam MCQ Series: Chemistry-I

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Chemistry Multiple Choice Questions For HCS Exam

Haryana Civil Services Exam 2020

Important 20000 MCQ Series For HCS Exam: CHEMISTRY PART-I

Q1. The main constituent of biogas is 

(a) oxygen

(b) methane

(c) acetic acid

(d) methyl alcohol

Explanation: Methane

Biogas comprises primarily methane (CH4) and carbon dioxide (CO2) and may have small amounts of hydrogen sulphide (H2S), moisture, and siloxanes.

Q2. Aspirin is chemically known as

(a) methyl salicylate

(b) hydroxy salicylate

(c) acetylsalicylic acid

(d) alkyl salicylic acid

Explanation: acetylsalicylic acid

Aspirin, also known as acetylsalicylic acid (ASA), is a medication used to reduce pain, fever, or inflammation.

Q3. The most abundant element in the human body is

(a) carbon 

(b) iron

(c) nitrogen

(d) oxygen

Explanation: Oxygen

Oxygen is the most abundant element in the human body. It makes up 65 percent of the total weight of a person.

Q4. A mixture of water and alcohol can be separated by

(a) Filtration 

(b) Evaporation

(c) Decantation

(d) Distillation 

Explanation: Distillation

To separate a mixture of alcohol (ethanol) and water, you can use a process known as fractional distillation. This technique relies on the fact that the compounds in the mixture have different boiling points.

Q5. Acid rain is caused due to pollution of atmosphere by

(a) oxides of carbon and nitrogen

(b) oxides of nitrogen and sulphur

(c) oxides of nitrogen and phosphorous  

(d) None of these

Explanation: oxides of nitrogen and sulphur

Acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.

Q6. Which of the following is biodegradable?

(a) Paper

(b) D.D.T.

(c) Aluminium

(d) Plastic

Explanation: Paper 

Paper is biodegradable because is made from plant materials and most plant materials are biodegradable. Paper is easily recycled and can be recycled up 6 or 7 times before the paper fibres become too short to be used for paper production.

Q7. The ‘Green House effect' is produced due to the presence of excess amount of

(a) Sulphur dioxide

(b) Nitrogen dioxide

(c) Carbon monoxide

(d) Methane 

Explanation:

By their percentage contribution to the greenhouse effect on Earth, the four major gases are: Water vapour (36-70%), Carbon dioxide (9-26%), Methane (4-9%), and Ozone (3-7%).

Q8. An element that does not occur in nature but can be produced artificially is

(a) thorium

(b) radium

(c) plutonium  

(d) uranium

Explanation: Plutonium (Pu) does not exist in nature. Plutonium and other so-called transuranic elements are considered by most to be man-made elements.

Q9. Chloroform can be used as

(a) Analgesic

(b) Anaesthetic

(c) Antimalarial

(d) Antibiotic

Explanation: Chloroform and halothane are potent anaesthetic agents which are also chemically related. Halothane was introduced into clinical anaesthesia in 1956 at a time when anaesthesia had been fully developed. Chloroform was first used in 1847 by James Young Simpson when anaesthesia was in its infancy.

Q10. The manufacture of iron from iron ore involves the process of

(a) oxidation

(b) reduction

(c) fractional distillation

(d) electrolysis

Explanation: The manufacture of iron ore involves the process of reduction. Important ores of iron: Haematite, Magnetite.

Q11. Which of the following is caused by the higher concentration of Nitrogen and Phosphorous?

(a) Eutrophication

(b) Hardness

(c) Alkalinity

(d) Acidity

Explanation: Eutrophication, the gradual increase in the concentration of phosphorus, nitrogen, and other plant nutrients in an aging aquatic ecosystem such as a lake. The productivity or fertility of such an ecosystem naturally increases as the amount of organic material that can be broken down into nutrients increases.

Q12. Earth’s atmosphere is an envelope of gases extending to a height of

(a) 100 km  

(b) 150 km

(c) 200 km

(d) 300 km

Explanation: The atmosphere of the Earth is an envelope of gases extending to a height of 200km.

Q13. Copper In its reaction with silver nitrate shows

(a) Oxidising property

(b) Reducing property

(c) Basic property

(d) Acidic property

Answer: b

Explanation: The silver nitrate reacts with copper to form hairlike crystals of silver metal and a blue solution of copper nitrate: 2 AgNO3 + Cu → Cu(NO3)2 + 2 Ag. 

Q14.The main source of carbon monoxide is

(a) Industrial process

(b) Fuel combustion

(c) Transportation

(d) Solid waste disposal

Explanation: The greatest sources of CO to outdoor air are cars, trucks, and other vehicles or machinery that burn fossil fuels.

Q15. ‘Aerosol’ is

(a) Suspended solid particles in air

(b) Pollutant gas, present in air

(c) Microbes, present in air

(d) Greenhouse gas present in air

ExplanationAn aerosol is a suspension of fine solid particles or liquid droplets in air or another gas. Aerosols can be natural or anthropogenic. Examples of natural aerosols are fog, mist, dust, forest exudates and geyser steam. Examples of anthropogenic aerosols are particulate air pollutants and smoke.

Q16. Philosopher's Wool is

(a) Zinc carbonate

(b) Zinc sulphate

(c) Zinc oxide

(d) Zinc blende 

Explanation: The compound zinc oxide (ZnO) is called philosopher's wool. Alchemists, as part of their rituals, would burn zinc in air and collect the residue, which formed into white woolly tufts. They called it lana philosophica in Latin, meaning philosopher's wool.

Q17. Synthetic detergents are made from

(a) Sodium stearate

(b) Sodium salt of benzene sulphonic acid

(c) Sodium salt of benzene carboxylic acid

(d) Sodium palmitate

Explanation: A synthetic detergent is a cleansing substance that acts similarly to soap, but is made from chemical compounds instead of fats and lye. These detergents were developed in order to overcome some of soap's shortcomings, such as soap's inability to lather in hard or acidic environments, as it is reliant on fats and oils. These substances are usually alkylbenzenesulfonates, a family of compounds that are similar to soap but are more soluble in hard water because the polar sulfonate (of detergents) is less likely than the polar carboxyl (of soap) to bind to calcium and other ions found in hard water. Synthetic detergents can be made from petrochemicals, fats, and oils. Detergents are commonly available as powders or concentrated solutions.

Q18.The sewage obtained from water closets and urinals is known as

(a) Sanitary waste

(b) Industrial waste

(c) Garbage  

(d) Sullage

Explanation: The sewage obtained from water closets and urinals are known as Sanitary waste.

Q19. The maximum permissible concentration of total hardness in drinking water is

(a) 50  

(b) 100

(c) 200

(d) 500

Explanation: The maximum permissible concentration of total hardness in drinking water is 200.

Q20. An electric fuse is an alloy of 

(a) tin and lead

(b) zinc and lead

(c) copper and iron

(d) carbon and tin

Explanation: The fuse wire is made up of Sn (tin) and Pb (lead) alloy because of its high resistance and low melting.

Q21. The chemical used for cloud seeding for artificial rains is

(a) Silver Nitrate

(b) Potassium Bromide

(c) Silver Iodide

(d) Potassium Nitrate

Explanation: The most common chemicals used for cloud seeding include silver iodide, potassium iodide, and dry ice (solid carbon dioxide). Liquid propane, which expands into a gas, has also been used. This can produce ice crystals at higher temperatures than silver iodide.

Q22. Tetraethyl lead (TEL) is 

(a) a catalyst in burning fossil fuel

(b) an antioxidant

(c) a reductant

(d) an antiknock compound

Explanation: Organic lead (tetraethyl lead; TEL) is used as an antiknock agent in gasoline and jet fuels. TEL is absorbed rapidly from the skin as well as the lungs and gastrointestinal tract and is converted to triethyl lead in the body. This form of lead may be responsible for its toxic effects.

Q23. In silvery paints, the main constituent present is 

(a) Aluminium powder

(b) Silver powder

(c) Lead powder

(d) White lead

Explanation: Silver paints contain powdered aluminium which gives the silvery appearance. Aluminium is the only metal that can maintain metallic lustre when made into a powder. The metal is not exactly a powder but very small flakes.

Q24. Which one of the following is a greenhouse gas?

(a) Nitrogen

(b) Helium

(c) Carbon dioxide

(d) Sulphur dioxide

Explanation: Greenhouse gases are those that absorb and emit infrared radiation in the wavelength range emitted by Earth. Carbon dioxide (0.04%), nitrous oxide, methane and ozone are trace gases that account for almost one tenth of 1% of Earth's atmosphere and have an appreciable greenhouse effect.

Q25. Which of the following is a method/process of disposing of solid waste which cannot be reused or recycled? 

(a) Landfills

(b) Incineration

(c) pyrolysis and Gasification

(d) All the above 

Explanation: All the above methods are of disposing of solid waste that cannot be reused or recycled.

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