1240+ Chemistry Solved MCQs

201.

Gunpowder consits of a mixture of –

A. sand and TNT
B. TNT and charcoal
C. nitre, sulphur and charcoal
D. sulphur, sand and charcoal
Answer» C. nitre, sulphur and charcoal
Explanation: Gunpowder, also known since the late 19th century as black powder, was the first chemical explosive and the only one known until the mid-1800s. It is a mixture of sulfur, charcoal, and potassium nitrate (saltpetre)— with the sulfur and charcoal acting as fuels, while the saltpeter works as an oxidizer. Because of its burning properties and the amount of heat and gas volume that it generates, gunpowder has been widely used as a propellant in firearms and as a pyrotechnic composition in fireworks.
202.

Litmus is obtained from –

A. a bacterium
B. a fungus
C. an alga
D. lichen
Answer» D. lichen
Explanation: Litmus is a water-soluble mixture of different dyes extracted from lichens, especially Roccellatinctoria. It is often absorbed onto filter paper to produce one of the oldest forms of pH indicator, used to test materials for acidity. Blue litmus paper turns red under acidic conditions and red litmus paper turns blue under basic (i.e. alkaline) conditions, with the colour change occurring over the pH range 4.5-8.3 at 25 degree C. Neutral litmus paper is purple. Litmus can also be prepared as an aqueous solution that functions similarly
203.

Vinegar made by fermentation from cane sugar contains –

A. palmitic acid
B. lactic acid
C. citric acid
D. acetic acid
Answer» D. acetic acid
Explanation: Vinegar is a liquid substance consisting mainly of acetic acid (CH3CO2H) and water, the acetic acid being produced through the fermentation of ethanol by acetic acid bacteria. It is today mainly used in the kitchen as a general cooking ingredient, but historically, as the most easily available mild acid, it had a great variety of industrial, medical, and domestic uses, some of which (such as a general household cleanser) are still promoted today. Commercial vinegar is produced either by fast or slow fermentation processes.
204.

Which of the following can be used to absorb neutrons to control the chain reaction during nuclear fission?

A. Boron
B. Heavy water
C. Uranium
D. Plutonium
Answer» A. Boron
Explanation: Boron shielding is used as a control for nuclear reactors, taking advantage of its high cross-section for neutron capture. Elemental boron is rare and poorly studied because the material is extremely difficult to prepare. Most studies on "boron" involve samples that contain small amounts of carbon. Chemically, boron behaves more similarly to silicon than to aluminium. Crystalline boron is chemicallyinert and resistant to attack by boiling hydrofluoric or hydrochloric acid.
205.

Bone ash contains -

A. Calcium sulphate
B. Phosphoric sulphate
C. Calcium phosphate
D. Calcium hypophosphate
Answer» C. Calcium phosphate
Explanation: Bone ash is a. white material produced by the calcination of bones. It is primarily composed of calcium phosphate. It is commonly used in fertilizers, polishing compounds and in making ceramics such as bone china. It also has historical uses in the manufacture of baking powders and assay cupels.
206.

The hardest substance available in earth is –

A. Platinum
B. Silicon
C. Diamond
D. Gold
Answer» C. Diamond
Explanation: Diamond is the hardest naturally occurring substance found on Earth. But it is not the hardest substance.
207.

potato tuber has been cut into two halves. A few drops of iodine solution are placed on the cut surface of one of the halves. What colour change will be noticed?

A. From brown to blue-black
B. From brown to orange-red
C. From blue to pink
D. From pink to blue-green
Answer» A. From brown to blue-black
Explanation: The Iodine test is used to test for the presence of starch. Iodine solution — iodine dissolved in an aqueous solution of potassium iodide — reacts with the starch producing a purple black colour.
208.

Lead pencil contains –

A. lead
B. ferrous sulphide
C. lead sulphide
D. graphite
Answer» D. graphite
Explanation: Most pencil cores are made of graphite mixed with a clay binder, leaving grey or black marks that can be easily erased. Graphite pencils are used for both writing and drawing, and the result is durable: although writing can usually be removed with an eraser, it is resistant to moisture, most chemicals, ultraviolet radiation and natural aging.
209.

Solder is an alloy of –

A. lead, zinc
B. copper, lead
C. tin, lead
D. sodium, lead
Answer» C. tin, lead
Explanation: Tin/lead solders, also called soft solders, are commercially available with tin concentrations between 5% and 70% by weight. The greater the tin concentration, the greater the solder's tensile and shear strengths. Alloys commonly used for electrical soldering are 60/40 Tin/lead (Sn/Pb) which melts at 370 °F or 188 °C and 63/37 Sn/Pb used principally in electrical/electronic work.
210.

What is the most common salt in sea water?

A. Calcium carbonate
B. Potassium chloride
C. Sodium chloride
D. Magnesium sulphate
Answer» C. Sodium chloride
Explanation: Sodium chloride, also known as salt, common salt, table salt or halite, is an ionic compound with the formula NaCl, representing equal proportions of sodium and chloride. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multi-cellular organisms.
211.

When quick lime is added to water

A. heat is liberated
B. heat is absorbed
C. temperature decreases
D. no heat change takes place
Answer» A. heat is liberated
Explanation: When quick lime is added to water, then a chemical reaction takes places and slaked lime is formed, evolving heat in this process. It makes the water boil.
212.

The umber of neutrons present in an element having mass number 226 and atomic number 88 is–

A. 88
B. 138
C. 314
D. 50
Answer» B. 138
Explanation: The mass number is a count of the number of particles in an atom's nucleus which is made up of protons and neutrons. In other words, Mass Number = Number of Protons + Number of Neutrons. The atomic number is the number of protons in an atom of an element, 226 = 88 + number of Neutrons. So, the number of neutrons= 226 - 88= 138.
213.

The atomic number of hydrogen is 1. This implies that it contains                in its K- shell.

A. One neutron
B. One proton
C. One electron
D. None of the above
Answer» C. One electron
Explanation: This implies that Hydrogen has one electron in its K shell. Also, it requires one more electron to fill the K shell. So two hydrogen atoms share their electrons to form a molecule of hydrogen, H2.
214.

Name two elements that find wide application in transistor industry –

A. Silicon and Germanium
B. Carbon and Platinum
C. Iridium and Germanium
D. Tungsten and Platinum
Answer» A. Silicon and Germanium
Explanation: A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power. Semiconductor material (date first used): the metalloids germanium (1947) and silicon (1954) — in amorphous, polycrystalline and mono- crystalline form; the compounds gallium arsenide (1966) and silicon carbide (1997), the alloy silicon-germanium (1989), the allotrope of carbon graphene (research ongoing since 2004), etc.
215.

The energy of the sun is mainly due to

A. nuclear fission
B. radioactivity
C. heat
D. nuclear fusion
Answer» D. nuclear fusion
Explanation: The Sun is a main-sequence star, and thus generates its energy by nuclear fusion of hydrogen nuclei into helium. Nuclear fusion is a nuclear reaction in which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus. During this process, matter is not conserved because some of the mass of the fusing nuclei is converted to photons which are released through a cycle that even our sun uses.
216.

Tear gas used by the police to disperse the mob contains -

A. Carbon dioxide
B. Chlorine
C. Ammonia
D. Hydrogen sulphide
Answer» B. Chlorine
Explanation: Tear gas, formally known as a lachrymatory agent, is a possibly lethal chemical weapon that stimulates the corneal nerves in the eyes to cause tears, pain, and even blindness.
217.

Epsom salt is used -

A. as purgative
B. in softening water
C. in paper industry
D. in making tooth paste
Answer» A. as purgative
Explanation: Magnesium sulfate is an inorganic salt (chemical compound) containing magnesium, sulfur and oxygen which is commonly called Epsom Salt. Because like other salts, it withdraws water from cells, Epsom salt is used as a fast-acting purgative in some types of poisoning, to draw water into the intestines, thus, reducing constipation; to withdraw toxins from the body; and to draw fluid from the brain in cases of cerebral edema.
218.

The ratio of pure gold in 18 carat gold is -

A. 100%
B. 80%
C. 75%
D. 60%
Answer» C. 75%
Explanation: The gold content of alloys is measured in carats (k). Pure gold is designated as 24k where the ratio of pure gold is supposed to be 100 per cent. So 18 k gold will have pure gold ratio of 75 per cent.
219.

Oil of vitriol is -

A. nitric acid
B. sulfuric acid
C. hydrochloric acid
D. phosphoric acid
Answer» B. sulfuric acid
Explanation: Sulfuric acid or was called "oil of vitriol" by medieval European alchemists because it was prepared by roasting "green vitriol" in an iron retort.
220.

The number of electrons in the outer shell of the most stable or inert atoms is

A. 1
B. 5
C. 3
D. 8
Answer» D. 8
Explanation: The innermost shell has a maximum of two electrons, but the next two electron shells can each have a maximum of eight electrons.
221.

Supersonic jet causes pollution by thinning of -

A. O3 layer
B. O2 layer
C. SO2 layer
D. CO2 layer
Answer» A. O3 layer
Explanation: Three forms (or allotropes) of oxygen are involved in the ozone-oxygen cycle: oxygen atoms (O or atomic oxygen), oxygen has (O2 or diatomic oxygen), and ozone gas (O3 or triatomic oxygen). Ozone is formed in the stratosphere when oxygen molecules photodissociate after absorbing an ultraviolet photon whose wavelength is shorter than 240 nm. This converts a single O2 into two atomic oxygen radicals. The atomic oxygen radicals then combine with separate O2 molecules to create two O3 molecules.
222.

Photoxidation process is initiated by –

A. light
B. heat
C. oxygen
D. catalyst
Answer» A. light
Explanation: Oxidation is a process in which something (an atom or molecule or substance) loses an electron to something else. Photo- oxidation is therefore the process of oxidation which is caused by shining light on it. Often, light can be used to cause reactions to happen, such as oxidation. The term "photo" comes from "photon" which is light. The effect is facilitated by radiant energy such as UV or artificial light. This process is the most significant factor in weathering of polymers.
223.

Ultraviolet radiation striking the earth is due to the depletion of –

A. carbon monoxide
B. carbon dioxide
C. ozone
D. oxygen
Answer» C. ozone
Explanation: Ozone is a powerful oxidant (far more so than dioxygen) and has many industrial and consumer applications related to oxidation. This same high oxidizing potential, however, causes ozone to damage mucus and respiratory tissues in animals, and also tissues in plants, above concentrations of about 100 parts per billion. This makes ozone a potent respiratory hazard and pollutant near ground level.
224.

In nuclear reactors, graphite is used as a/an –

A. fuel
B. lubricant
C. moderator
D. insulator
Answer» C. moderator
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. In nuclear engineering, a neutron moderator is a medium that reduces the speed of fast neutrons, thereby turning them into thermal neutrons capable of sustaining a nuclear chain reaction involving uranium-235.
225.

Sea water can be purified by the process of –

A. distillation
B. evaporation
C. filtration
D. fractional distillation
Answer» A. distillation
Explanation: The traditional process used in desalination operations is vacuum distillation— essentially the boiling of water at less than atmospheric pressure and thus a much lower temperature than normal. This is because the boiling of a liquid occurs when the vapor pressure equals the ambient pressure and vapor pressure increases with temperature.
226.

Which is/ are the important raw materials in cement industry?

A. Limestone
B. Gypsum and Clay
C. Clay
D. Limestone and Clay
Answer» D. Limestone and Clay
Explanation: Limestone Claimed Clay Cement is a low-carbon alternative to the standard Portland cement. LC3 can reduce CO2 emissions related to cement manufacturing of cement by reducing the amount of clinker, replacing it with limestone and claimed clays.
227.

The father of modern chemistry is –

A. Priestley
B. Lavoisier
C. Dalton
D. Mendeleeff
Answer» B. Lavoisier
Explanation: Antoine Lavoisier was a French nobleman and chemist central to the 18th- century chemical revolution and a large influence on both the history of chemistry and the history of biology.
228.

The acid rain destroys vegetations because it contains –

A. nitric acid
B. ozone
C. carbon monoxide
D. sulphuric acid
Answer» D. sulphuric acid
Explanation: Acid rain is a rain or any other form of precipitation that is unusually acidic, meaning that it possesses elevated levels of hydrogen ions (low pH). It can have harmful effects on plants, aquatic animals, and infrastructure. Acid rain is caused by emissions of sulfur dioxide and nitrogen oxides, which react with the water molecules in the atmosphere to produce acids. Governments have made efforts since the 1970s to reduce the release of sulfur dioxide into the atmosphere with positive results.
229.

Diamonds are glittering and attractive because light incident on them undergoes –

A. highest refraction
B. multiple internal reflections
C. multiple surface reflections
D. hundred percent transmission
Answer» B. multiple internal reflections
Explanation: Diamond has remarkable optical characteristics. Because of its extremely rigid lattice, it can be contaminated by very few types of impurities, such as boron and nitrogen. Combined with wide transparency', this resultsin the clear, colourless appearance of most natural diamonds. Small amounts of defects or impurities (about one per million of lattice atoms) colour diamond blue (boron), yellow (nitrogen), brown (lattice defects), green (radiation exposure), purple, pink, orange or red.
230.

Which of the following is a supercooled liquid?

A. Ice Cream
B. Teflon
C. Glass
D. Mercury
Answer» C. Glass
Explanation: Most of us think as glass as a solid material, but it is actually a super cooled liquid. Molecular units have a disordered arrangement yet still have sufficient cohesion that mechanical rigidity is produced. Glass was first made in the Middle East, approximately during the third millennium BC. Early uses were primarily for vessels or decoration.
231.

On heating, Gypsum loses certain percentage of its water content and becomes

A. Chalk
B. Calcium sulphate
C. Plaster of Paris
D. a pearl
Answer» C. Plaster of Paris
Explanation: Plaster of paris, quick-setting gypsum plaster consisting of a fine white powder (calcium sulfate hemihydrate), which hardens when moistened and allowed to dry.
232.

What is the element required for solar energy conversion?

A. Beryllium
B. Tantalum
C. Silicon
D. Ultra pure carbon
Answer» C. Silicon
Explanation: The most prevalent bulk material for solar cells is crystalline silicon (abbreviatedas a group as c-Si), also known as "solar grade silicon". Bulk silicon is separated into multiple categories according to crystallinity and crystal size in the resulting ingot, ribbon, or wafer.
233.

What is the chemical name for `Baking Soda'?

A. Sodium carbonate
B. Sodium bicarbonate
C. Sodium nitrite
D. Sodium nitrate
Answer» B. Sodium bicarbonate
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).
234.

The first metal used by a man was –

A. Copper
B. Silver
C. Bronze
D. Brass
Answer» A. Copper
Explanation: Copper occurs naturally as native copper and was known to some of the oldest civilizations on record. It has a history of use that is at least 10,000 years old, and estimates of its discovery place it at 9000 BC in the Middle East; a copper pendant was found in northern Iraq that dates to 8700 BC. There is evidence that gold and meteoric iron (but not iron smelting) were the only metals used by humans before copper.
235.

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

A. Kerosene
B. Lime
C. Oxalic acid solution
D. Petrol
Answer» C. Oxalic acid solution
Explanation: Oxalic acid is an organic compound with the formula H2C2O2. It is a colourless crystalline solid that dissolves inwater to give colourless solutions. It is classified as a dicarboxylic acid. In terms of acid strength. it is much stronger than acetic acid. Oxalic acid is a reducing agent and its conjugate base, known as oxalate , is a chelating agent for metal cations.
236.

The substance most commonly used as a food preservative is –

A. sodium carbonate
B. tartaric acid
C. acetic acid
D. sodium salt of benzoic acid
Answer» D. sodium salt of benzoic acid
Explanation: A preservative is a naturally occurring or synthetically produced substance that is added to products such as foods, pharmaceuticals, paints, biological samples, wood, etc. to prevent decomposition by microbial growth or by undesirable chemical changes. Preservative food additives can be used alone or in conjunction with other methods of food preservation. Preservatives may be antimicrobial preservatives, which inhibit the growth of bacteria or fungi, including mold or they can be antioxidants such as oxygen absorbers, which inhibit the oxidation of food constituents.
237.

What among following is used to produce artificial rain?

A. copper oxide
B. carbon monoxide
C. silver iodide
D. silver nitrate
Answer» C. silver iodide
Explanation: Artificial rain is produced by spraying clouds with substances like Silver Iodide (costly) or cheaper ones like solid carbon dioxide (dry ice) or even finely powdered Sodium Chloride.
238.

Detergents clean surfaces on the principle of –

A. viscosity
B. surface tension
C. elasticity
D. floatation
Answer» B. surface tension
Explanation: Detergents and soaps are used for cleaning because pure water can't remove oily, organic soiling. Soap cleans by acting as an emulsifier. Basically, soap allows oil and water to mix so that oily grime can be removed during rinsing. Detergents were developed in response to the shortage of the animal and vegetable fats used to make soap during World War I and World War II. Detergents are primarily surfactants, which could be produced easily from petrochemicals.
239.

Which of the following is ozone depleting pesticide?

A. D.D.T.
B. Benzene
C. Methyl bromide
D. Ethylene ozonide
Answer» C. Methyl bromide
Explanation: Methyl bromide- is considered to be a significant ozone depleting substance (ODS) by atmospheric scientists. While methyl bromide is a natural substance, the additional methyl bromide added to the atmosphere by humans contributes to the thinning of the ozone layer, allowing increased UV radiation to reach the earth's surface, with potential impact not only to human health and the environment, but to agricultural crops as well.
240.

Galvanised iron is made by coating iron with –

A. Zinc
B. Nickel
C. Chromium
D. Sulphur
Answer» A. Zinc
Explanation: Galvanization) is the process of applying a protective zinc coating to steel or iron, in order to prevent rusting, Although galvanization can be done with electrochemical and electro-deposition processes, the mostcommon method in current use is hot-dip galvanization, in which steel parts are submerged in a bath of molten zinc.
241.

An atomic pile is used for –

A. producing X-rays
B. conducting nuclear fission
C. coducting thermonuclear fusion
D. accelerating atoms
Answer» B. conducting nuclear fission
Explanation: An atomic pile is a nuclear reactor that uses controlled nuclear fission to generate energy. The most common reactor consists of a large assembly of graphite (an allotropic form of carbon) blocks having rods of uranium metal (fuel).
242.

Which of the following type of coal has the lowest proportion of volatile matter?

A. Lignite
B. Peat
C. Bituminous
D. Anthracite
Answer» D. Anthracite
Explanation: Anthracite has the lowest proportion of volatile matter. Volatile matter in coal refers to the components of coal, except for moisture, which are liberated at high temperature in the absence of air. This is usually a mixture of short and long chain hydrocarbons, aromatic hydrocarbons and some sulfur. The volatile matter of coal is determined under rigidly controlled standards.
243.

The compound to which H2 does not add is –

A. Biphenyl ethylene
B. Tetraphenyl ethylene
C. Tetra - a - naphthylethylene
D. Tetra - 9 - phenanthrylethylene
Answer» B. Tetraphenyl ethylene
Explanation: While H2 is not very reactive under standard conditions, it does form compounds with most elements. Millions of hydrocarbons are known, but they are notformed by the direct reaction of elementary hydrogen and carbon. Hydrogen can form compounds with elements that are more electronegative, such as halogens. Hydrogen forms a vast array of compounds with carbon.
244.

Major gaseous pollutant of the thermal power station is –

A. H2S
B. NH3
C. NO2
D. SO2
Answer» D. SO2
Explanation: A flue-gas stack is a type of chimney, a vertical pipe, channel or similar structure through which combustion product gases called flue gases are exhausted to the outside air. Flue gases are produced when coal, oil, natural gas, wood or any other fuel is combusted in an industrial furnace, a power plant's steam-generating boiler, or other large combustion device. Flue was is usually composed of carbon dioxide (CO2) and water vapor as well as nitrogen and excess oxygen remaining from the intake combustion air.
245.

The process of removing calcium and magnesium from hard water is known as –

A. Sedimentation
B. Filtration
C. Flocculation
D. Water softening
Answer» D. Water softening
Explanation: Water softening is the reduction of the concentration of calcium, magnesium, and certain other metal cations in hard water. Hardness ions dissolved in water can cause a variety of undesired effects including interfering with the action of soaps, the buildup oflimescale, which can foul plumbing, and galvanic corrosion. Conventional water-softening appliances intended for household use depend on an ion-exchange resin in which hardness ions are exchanged for sodium ions.
246.

Which of the following metals causes Itai-Itai disease?

A. Cadmium
B. Chromium
C. Cobalt
D. Copper
Answer» A. Cadmium
Explanation: Itai-itai disease was the documented case of mass cadmium poisoning in Toyama Prefecture, Japan, starting around 1912. The cadmium poisoning caused softening of the bones and kidney failure. The disease is named for the severe pains caused in the joints and spine. The cadmium was released into rivers by mining companies in the mountains. The mining companies were successfully sued for the damage. Itai-itai disease is known as one of the Four Big Pollution Diseases of Japan.
247.

Which is used in preparation of dynamite?

A. glycerol
B. ethyl alcohol
C. methyl alcohol
D. glycol
Answer» A. glycerol
Explanation: Dynamite is an explosive made of nitroglycerin, sorbents (such as powdered shells or clay) and stabilizers. It was invented by the Swedish chemist and engineer Alfred Nobel in Geesthacht, and patented in 1867.
248.

Vinegar is the trade name of -

A. acetic acid
B. chloroform
C. carbon tetrachloride
D. ethyl alcohol
Answer» A. acetic acid
Explanation: The trivial name acetic acid is the most commonly used and preferred IUPAC name. The systematic name ethanoic acid, a valid IUPAC name, is constructed according to the substitutive nomenclature.
249.

Acid secretion is characteristic of -

A. Buccal cavity
B. Stomach
C. Small intestine
D. Large intestine
Answer» B. Stomach
Explanation: The stomach is famous for its secretion of hydrochloric acid. It is secreted from parietal cells into the lumen where it establishes an extremely acidic environment. This acid is important for activation of pepsinogen and inactivation of ingested microorganisms such as bacteria.
250.

Which one of the following is not a fertilizer?

A. Ammonium sulphate
B. Calcium sulphate
C. Calcium ammonium nitrate
D. Potassium nitrate
Answer» B. Calcium sulphate
Explanation: Calcium sulfate is a common laboratory and industrial chemical. In the form of -anhydrite (the nearly anhydrous form), it is used as a desiccant. It is also used as a coagulant in products like tofu. The main sources of calcium sulfate are naturally occurring gypsum and anhydrite which occur at many locations worldwide as evaporites.
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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