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1240+ Chemistry Solved MCQs

These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: General Knowledge (GK) .

251.

The common refrigerant in domestic refrigerator is -

A. Neon
B. Oxygen
C. Nitrogen
D. Freon
Answer» D. Freon
Explanation: Common refrigerants used in domestic refrigerators are freon, neon and nitrogen. It flows through four components of refrigerator again and again. These four components are cooling chamber, compressor, heat exchanger and expander
252.

The chemical name of “laughing gas” is -

A. Nitric oxide
B. Nitrogen dioxide
C. Nitrogen pentoxide
D. Nitrous oxide
Answer» D. Nitrous oxide
Explanation: Nitrous oxide, commonly known as laughing gas, is a chemical compound with the formula N2O. It is used in surgery and dentistry for its anesthetic and analgesic effects. It is known as "laughing gas" due to the euphoric effects of inhaling it, a property that has led to its recreational use as a dissociative anesthetic.
253.

Which of the following is used to remove ink and rust stains on cloth?

A. Oxalic acid
B. Alcohol
C. Ether
D. Kerosene oil
Answer» A. Oxalic acid
Explanation: Oxalic acid is a reducing agent and its conjugate base, known as oxalate, is a chelating agent for metal cations and stain removal. Oxalic acid's main applications include cleaning or bleaching, removal of stains on clothes and the removal of rust.
254.

Bleaching action of chlorine is by -

A. decomposition
B. hydrolysis
C. reduction
D. oxidation
Answer» D. oxidation
Explanation: Chlorine bleaches by the process of oxidation. It needs moisture for its bleaching action. Chlorine reacts with water to form hydrochloric and hypochlorous acids.
255.

Hardest material is -

A. Tungsten
B. Diamond
C. Steel
D. Graphite
Answer» B. Diamond
Explanation: Diamondsare commonly known as the hardest substance on earth, used in drill bits for cutting applications.
256.

When iron rusts, its weight -

A. decreases
B. increases
C. Constant
D. None
Answer» B. increases
Explanation: Iron rust when they come into contact with water and oxygen. They rust faster in salty water or acid rain.
257.

Two elements which can form a large number of compounds are

A. Carbon and Hydrogen
B. Carbon and Nitrogen
C. Carbon and Oxygen
D. Carbon and Sulphur
Answer» A. Carbon and Hydrogen
Explanation: The carbon-hydrogen bond (C-H bond) is a bond between carbon and hydrogen atoms that can be found in many organic compounds. Compound classes consisting solely of C-H bonds and C-C bonds are alkanes, alkenes, alkynes, and aromatic hydrocarbons. Collectively they are known as hydrocarbons.
258.

An inert gas mixed with oxygen given to patients suffering from restricted breathing is –

A. Helium
B. Krypton
C. Radon
D. Argon
Answer» A. Helium
Explanation: Heliox is a breathing has composed of a mixture of helium (He) and oxygen (O2). Heliox has been used medically since the 1930s, and although the medical community adopted it initially to alleviate symptoms of upper airway obstruction, its range of medical uses has since expanded greatly, mostly because of the low density of the gas
259.

Brass is an alloy of -

A. Lead and tin
B. Zine and copper
C. Antimony, tin and lead
D. Zinc, tin and copper
Answer» B. Zine and copper
Explanation: Brass is an alloy of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties. By comparison, bronze is principally an alloy of copper and tin. Bronze does not necessarily contain tin, and a variety of alloys of copper, including alloys with arsenic, phosphorus, aluminium, manganese, and silicon, are commonly termed "brome".
260.

The chemical name of rat poison is -

A. zinc oxide
B. potassium cyanide
C. lead nitrate
D. zinc phosphide
Answer» D. zinc phosphide
Explanation: Zinc phosphide is used as a rodenticide. A mixture of food and zinc phosphide is left where the rodents can eat it. The acid in the digestive system of the rodent reacts with the phosphide to generate the toxic phosphine gas.
261.

Slag is a name given for -

A. molten iron
B. molten sand
C. molten alumina
D. molten calcium silicate
Answer» C. molten alumina
Explanation: Slag is a partially vitreous by- product of the process of smelting ore, which separates the desired metal fraction from the unwanted fraction. A good example is steelmaking slag: quicklime and magnesite are introduced for refractory protection, neutralizing the alumina and silica separated from the metal, and assist in the removal of sulfur and phosphorus from the steel.
262.

Which one of the following statements is not correct? Vulcanisation of rubber makes it -

A. soft and flexible
B. strong and hard
C. chemical resistant
D. withstand higher temperatures
Answer» A. soft and flexible
Explanation: In order to give more strength and more elasticity, natural rubber is heated with sulphur or sulphur compounds at 150°C temperature. Vulcanized rubber has good tensile strength. The working temperature of vulcanized rubber is enhanced up to 100°C. It has good resistance to organic solvents.
263.

Stainless steel is an alloy of -

A. chromium and carbon
B. chromium, carbon and iron
C. chromium and iron
D. carbon and iron
Answer» B. chromium, carbon and iron
Explanation: Steel is an alloy made by combining iron and other elements, the most common of these being carbon. When carbon is used, its content in the steel is between 0.2% and 2.1% by weight, depending on the grade. Other alloying elements sometimes used are manganese, chromium, vanadium and tungsten. Stainless steel s defined as a steel alloy with a minimum of 10.5% to 11% chromium content by mass. Stainless steel differs from carbon steel by the amount of chromium present.
264.

For generation of biogas, the materials commonly used are —

A. Animal wastes
B. Crop residues
C. Aquatic plants
D. Forest residues
Answer» A. Animal wastes
Explanation: Biogas typically refers to a gas produced by breakdown of organic matter in the absence of oxygen. Organic waste such as dead plant and animal material, animal feces, and kitchen waste can be converted into a gaseous fuel called biogas. Biogas originates from biogenic material and is a type of bio fuel. Biogas is produced by the anaerobic digestion or fermentation of biodegradable materials such as biomass, manure, sewage, municipal waste, green waste, plant material, and crops.
265.

Which one of the following minerals is found in Monazite sand?

A. Potassium
B. Uranium
C. Thorium
D. Sodium
Answer» C. Thorium
Explanation: Monazite is a reddish-brown phosphate mineral containing rare earth metals. It occurs usually in small isolated crystals. There are actually at least four different kinds of monazite, depending on relative elemental composition of the mineral. Monazite is an important are for thorium, lanthanum, and cerium. It is often found in placer deposits. The deposits in India are particularly rich in monazite. It has a hardness of 5.0 to 5.5 and is relatively dense, about 4.6 to 5.7 g/ cm3.
266.

Now-a-days yellow lamps are frequently used as street lights. Which of the following gases is used in these lamps?

A. Sodium
B. Neon
C. Hydrogen
D. Nitrogen
Answer» A. Sodium
Explanation: A sodium-vapor lamp is a gas- discharge lamp that uses sodium in an excited state to produce light. There are two varieties of such lamps: low pressure and high. pressure. Low-pressure sodium lamps are the most efficient electrical light sources, but their yellow light restricts applications to outdoor lighting such as street lamps. High-pressure sodium lamps have a broader spectrum of light but poorer colour rendering than other types.
267.

The tip of the match-stick contains –

A. phosphorus pentoxide
B. white phosphorus
C. red phosphorus
D. phosphorus trichloricle
Answer» C. red phosphorus
Explanation: A typical modern match is made of a small wooden stick or stiff paper. One end is coated with a material that can be ignited by frictional heat generated by striking the match against a suitable surface. Matches are usually sold in quantity; wooden ones are packaged in boxes, and paper matches are clustered in rows stapled into matchbooks. They are commonly sold by tobacconists and many other kinds of shops.
268.

Commercially, sodium bicarbonate is known as –

A. Washing soda
B. Baking soda
C. Bleaching powder
D. Soda ash
Answer» B. Baking soda
Explanation: Sodium bicarbonate or sodium hydrogen carbonate is the chemical compound with the formula NaHCO3. Sodium bicarbonate is a white solid that is crystalline but often appears as a fine powder. It has a slightly salty, alkaline taste resembling that of washing soda (sodium carbonate). The natural mineral form is nahcolite. It is a component of the mineral patron and is found dissolved in many mineral springs.
269.

Which gas does not form the part, of atmosphere?

A. Nitrogen
B. Helium
C. Chlorine
D. None of the above
Answer» C. Chlorine
Explanation: The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night (the diurnal temperature variations). Air is the name given to the atmosphere used in breathing and photosynthesis.
270.

The reaction between an acid and a base to give a salt and water is known as a -

A. Neutralisation reaction
B. Reduction reaction
C. Oxidation reaction
D. Exothermic reaction
Answer» A. Neutralisation reaction
Explanation: The effect of a base is nullified by an acid and vice-versa. Example: Reaction of Sodium hydroxide with hydrochloric acid- NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l)
271.

Which of the following elements is obtained from sea weeds?

A. Argon
B. Sulphur
C. Vanadium
D. Iodine
Answer» D. Iodine
Explanation: Ribbon seaweeds(sp. laminaria) contain iodine compounds which they obtain by extracting iodide ions from seawater.
272.

Which of the following gases is most toxic?

A. Carbon dioxide
B. Carbon monoxide
C. Sulphur dioxide
D. Chlorine
Answer» B. Carbon monoxide
Explanation: Carbon monoxide (CO) is a colourless, odorless, and tasteless gas that is slightly lighter than air. It is toxic to humans and animals when encountered in higher concentrations, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal biological functions. In the atmosphere it is spatially variable, short lived, having a role in the formation of groundlevel ozone. Carbon monoxide is colourless, odorless, and tasteless, but highly toxic.
273.

Electron affinity of noble gases is -

A. zero
B. Low
C. High
D. Very high
Answer» A. zero
Explanation: Most elements 'want' to have a complete electron shell with 8 electrons. Since the Noble Gases already have that 'perfect status' then they have an affinity of 0.
274.

Curd is sour due to presence of –

A. Tartaric acid
B. Lactic acid
C. Acetic acid
D. Oxalic acid
Answer» B. Lactic acid
Explanation: Curds are a dairy product obtained by curdling (coagulating) milk with rennet or an edible acidic substance such as lemon juice or vinegar, and then draining off the liquid portion. The increased acidity causes the milk proteins (casein) to tangle into solid masses, or curds. The remaining liquid, which contains only whey proteins, is the whey.
275.

Tear gas is –

A. Chloroprene
B. Carbonyl chloride
C. Nitrous oxide
D. Bleaching powder
Answer» B. Carbonyl chloride
Explanation: Tear gas, formally known as a lachrymatory agent or ladnymator (from lacrima meaning "tear" in Latin), is a non-lethal chemical weapon that stimulates the corneal nerves in the eyes to cause tears, pain, and even blindness. Common lachrymators include OC, CS, CR, CN (phenacyl chloride), nonivarnide, bromoacetone, xylyl bromide and syn- propanethial-S-oxide (from onions). Tear gas works by irritating mucous membranes in the eyes, nose, mouth and lungs, and causes crying, sneezing, coughing, difficulty breathing, pain in the eyes, temporary blindness, etc. Lachrymators are thought to act by attacking sulphydryl functional groups in enzymes.
276.

Saccharin is made up of –

A. Toluene
B. Phenol
C. Propane
D. Butane
Answer» A. Toluene
Explanation: Saccharin can be produced in various ways. The original route by Remsen & Fahlberg starts with toluene. Saccharin ism artificial sweetener. The basic substance, benzoic sulfiloine, has effectively no food energy and is much sweeter than sucrose, but has a bitter or metallic aftertaste, especially at high concentrations. It is used to sweeten products such as drinks, candies, cookies, medicines, and toothpaste.
277.

PVC is obtained by the polymerisation of –

A. Propane
B. Vinyl chloride
C. Styrene
D. Acetylene
Answer» B. Vinyl chloride
Explanation: Polyvinyl chloride is produced by polymerization of the monomer vinyl chloride (17CM). Polyvinyl chloride, commonly abbreviated PVC, is the third-most widely produced plastic, after polyethylene and polypropylene. PVC is used in construction because it is cheaper and stronger than more traditional alternatives such as copper or ductile iron.
278.

Which of the following gases is present under pressure in soft drinks?

A. Oxygen
B. Nitrogen
C. Carbon dioxide
D. Nitrous oxide
Answer» C. Carbon dioxide
Explanation: Carbon dioxide is present under pressure in soft drinks. Carbon dioxide adds that special sparkle and bite to the beverage and also acts as a mild preservative. Carbon dioxide is an uniquely suitable was for soft drinks because it is inert, non-toxic, and relatively inexpensive and easy to liquefy.
279.

The substance which does not expand on going from liquid state to solid state is –

A. Water
B. Cast-iron
C. Aluminium
D. Type metal
Answer» D. Type metal
Explanation: In printing, type metal (sometimes called hot metal) refers to the metal alloys used in traditional type founding and hot metal typesetting. Lead is the main constituent of these alloys. Antimony and tin are added to make the character produced durable and tough while reducing the difference between the coefficients of expansion of the matrix and the alloy. Pure metal melts and solidifies in a simple manner at a specific temperature. This is not the case with alloys.
280.

Isobars are lines joining places having equal –

A. Rainfall
B. Pressure
C. Population
D. Height above sea-level
Answer» B. Pressure
Explanation: An isobar is a line of equal or constant pressure on a graph, plot, or map; an isopleth or contour line of pressure. More accurately, isobars are lines drawn on a map joining places of equal average atmospheric pressure reduced to sea level for a specified period of time. In meteorology, the barometric pressures shown are reduced to sea level, not the surface pressures at the map locations. The distribution of isobars is closely related to the magnitude and direction of the wind field, and can be used to predict future weather patterns.
281.

Global warming is mainly due to accumulation of –

A. Oxides of nitrogen
B. Oxides of sulphur
C. Carbon dioxide
D. Carbon monoxide
Answer» C. Carbon dioxide
Explanation: Global Warming refers to average increase in the earth's temperature due to increase in pollution which results in greenhouse effect which in turn leads to climate change. Global warming may lead to rise in the sea level due to melting of glaciers, shrinkage of forests, changes in the rainfall pattern and wide range of impacts on plants and humans. The greenhouse gases such as carbon dioxide accumulate into the atmosphere and trap heat that would normally exit into the outer space.
282.

Which is abundant in Gobar gas?

A. Carbon dioxide
B. Methane
C. Oxygen
D. Hydrogen
Answer» B. Methane
Explanation: Bio gas is a clean unpolluted and cheap source of energy in rural areas. It consists of 55-70% methane which is inflammable. Bio gas is produced from cattle dung in a bio gas plant commonly known as gobar gas plant through a process called digestion. It helps in reducing the deforestation as it arrests for cutting of trees for firewood.
283.

The most suitable vessel for storing concentrated sulphuric acid is –

A. Copper vessel
B. Aluminium vessel
C. Glass vessel
D. Earthen vessel
Answer» C. Glass vessel
Explanation: Concentrated Sulfuric acid can only be stored in glass, no metal lids, some plastic containers. It will attack anything organic, causing severe burns, the good thing is it will not start a fire but if it goes into contact with a metal it may generate hydrogen gas, an explosion risk.
284.

The radioactive element used in heart pacemakers is –

A. Uranium
B. Deuterium
C. Plutonium
D. Radium
Answer» A. Uranium
Explanation: The actinides (or actinoids) are the chemical elements with atomic numbers between 90 and 109 inclusively. They occur between Groups 3 and 4 in Period 7 of the periodic table. All elements in this family are radioactive. Five actinides namely: thorium,protoactinium, uranium, neptunium, and plutonium have been found in nature. Plutonium is used in the manufacture of nuclear weapons and as the power source in nuclear power plants. On a smaller scale, it is also used as a power source in smaller devices such as the heart pacemaker.
285.

The element which is commonly used in nuclear for producing electricity by nuclear fission is –

A. Radium
B. Plutonium
C. Uranium
D. Deuterium
Answer» C. Uranium
Explanation: Uranium is used to produce a chemical and nuclear reaction which makes a lot of heat.
286.

Which amidst the following is not a gem stone?

A. Cat's-eye
B. Topaz
C. Opal
D. Pearl
Answer» A. Cat's-eye
Explanation: A gemstone or gem (also called a precious or semi-precious stone, a fine gem, or jewel) is a piece of mineral, which, in cut and polished form, is used to make jewelry or other adornments.
287.

Which of the following vegetable oils does not contain essential fatty acids?

A. Sunflower oil
B. Mustard oil
C. Coconut oil
D. Gmundnut oil
Answer» A. Sunflower oil
Explanation: Fatty Acids are aliphatic carboxylic acid with varying hydrocarbon lengths at one end of the chain joined to terminal carboxyl (-COOH) group at the other end.
288.

Which of the following compounds is commonly used as an antiseptic in mouthwashes and toothpastes?

A. Borax
B. Saltpetre
C. Hydrogen peroxide
D. Sodium chloride
Answer» D. Sodium chloride
Explanation: Antiseptics are antimicrobial substances that are applied to living tissue/skin to reduce the possibility of infection, sepsis, or putrefaction. Antiseptics are generally distinguished from antibiotics by the latter's ability to be transported through the lymphatic system to destroy bacteria within the body, and from disinfectants, which destroy microorganisms found on non-living objects.
289.

Which one of the following is used to restore the colour of old oil-paintings?

A. Ozone
B. Hydrogen peroxide
C. Barium peroxide
D. Sodium peroxide
Answer» B. Hydrogen peroxide
Explanation: Hydrogen peroxide (H2O2) is the simplest peroxide (a compound with an oxygen- oxygen single bond). It is also a strong oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colourless. Due to its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent. The oxidizing capacity of hydrogen peroxide is so strong that it is considered a highly reactive oxygen species.
290.

A mixture of benzene and toluene forms

A. Non-ideal solution
B. Ideal solution
C. Emulsion
D. Suspension
Answer» B. Ideal solution
Explanation: A mixture of benzene and toluene (60 mole% toluene) enters a distillation column to be separated into two product streams.
291.

The aqueous solution of which acids is called Vinegar -

A. Citric acid
B. Hydrochloric acid
C. Acetic acid
D. Oxalic acid
Answer» C. Acetic acid
Explanation: Vinegar is an aqueous solution of acetic acid and trace chemicals that may include flavorings. Vinegar typically contains 5–20% acetic acid by volume.
292.

What happens to its potential energy when an object is taken to high altitude?

A. Its potential energy increases
B. Its potential energy decreases
C. Its potential energy remain same
D. None of the above
Answer» A. Its potential energy increases
Explanation: When an object is taken to high altitude its potential energy increases.
293.

Which one of the following noble gases is not found in the atmosphere?

A. Argon
B. Krypton
C. Radon
D. Xenon
Answer» C. Radon
Explanation: All the noble gases are present in Earth's atmosphere and, except for helium and radon, their major commercial source is the air, from which they are obtained by liquefaction and fractional distillation.
294.

The fuel used in an atomic reactor is –

A. Coal
B. Petrol
C. Combustable gases
D. Uranium
Answer» D. Uranium
Explanation: A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Most commonly they are used for generating electricity and for the propulsion of ships. Usually heat from nuclear fission is passed to a working fluid (water or gas), which runs through turbines that power either ship's propellers or generators. Some produce isotopes for medical and industrial use, and some are run only for research.
295.

Mortar is a mixture of water sand and

A. Slaked lime
B. Quick lime
C. Limestone
D. Gypsum
Answer» A. Slaked lime
Explanation: Mortar is a workable paste used to bind construction blocks together and fill the gaps between them. The blocks may be stone, brick, cinder blocks, etc. Mortar becomes hard when it sets, resulting in a rigid aggregate structure. Modern mortars are typically made from a mixture of sand, a binder such as cement or lime (slaked), and water. Mortar can also be used to fix, or point, masonry when the original mortar has washed away.
296.

The element which is used for vulcanizing rubber –

A. Sulphur
B. Bromine
C. Silicon
D. Phosphorus
Answer» A. Sulphur
Explanation: Vulcanisation is a chemical process for converting rubber or related polymers into more durable materials via the addition of sulfur or other equivalent "curatives" or "accelerators". By far the most common vulcanizing methods depend on sulfur.
297.

Which of the following is responsible for the extra strength of pyrex glass?

A. Potassium Carbonate
B. Lead Oxide
C. Borax
D. Ferric Oxide
Answer» C. Borax
Explanation: Older clear-glass Pyrex manufactured by Corning before 1998, Arc International's Pyrex products, and Pyrex laboratory glassware is made of borosilicate glass. According to the National Institute of Standards and Technology, borosilicate Pyrex is composed of (as percentage of weight): 14% boron, 51% oxygen, 0.3% sodium, 1% aluminium, 38% silicon, and less than 1% potassium. Pyrex glass cookware manufactured by World Kitchen is made of tempered soda- lime glass instead of borosilicate.
298.

Raw materials used for the manufacture of glass are –

A. sand, soda, limestone
B. sand, charcoal, soda
C. limestone, charcoal, sulphur
D. sand, sulphur, soda
Answer» A. sand, soda, limestone
Explanation: Quartz sand (silica) is the main raw material in commercial glass production. While fused quartz (primarily composed of SiO2) is used for some special applications, it is not very common due to its high glass transition temperature of over 1200 degree C (2192 degree F). Normally, other substances are added to simplify processing.
299.

Which of the following is used in welding broken pieces of iron rails and machine parts?

A. Aluminium sulphate
B. Solder
C. Aluminium powder
D. None of the above
Answer» C. Aluminium powder
Explanation: Aluminum powder is a highly flammable powder created by grinding aluminum into fine grains of material. In times past, this flammable metal powder was used in photography to create bright flashes during a photographic session. Today, aluminum powder is one of the tools utilized in various applicationsof pyrotechnics, including the creation of fireworks displays.
300.

Stainless steel is usually made by alloying the steel with –

A. copper and nickel
B. copper and chromium
C. chromium and nickel
D. manganese and copper
Answer» C. chromium and nickel
Explanation: In metallurgy, stainless steel is defined as a steel alloy with a minimum of 10.5 per cent to 11 per cent chromium content by mass. There are different types of stainless steels: when nickel is added, for instance, the austenite structure of iron is stabilized. This crystal structure makes such steels virtually non- magnetic and less brittle at low temperatures. For greater hardness and strength, more carbon is added.

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