1240+ Chemistry Solved MCQs


J. B. Sumner isolated first enzyme from Jackbeans as-

A. amylase
B. trypsin
C. urease
D. renin
Answer» C. urease
Explanation: James Batcheller Sumner (November 19, 1887 – August 12, 1955) was an American chemist. He discovered that enzymes can be crystallized.

Highest percentage of carbon is found in which form of coal?

A. Anthracite
B. Bituminous
C. Peat
D. Lignite
Answer» A. Anthracite
Explanation: Anthracite is the highest rank of coal since it has a carbon content of over 87% on a dry ash-free basis. Anthracite coal generally has the highest heating value per ton on a mineral-matter-free basis. It has a bright luster and breaks with a semi-conchoidal. fracture.

The chemical that is used to ripen mangoes is -

A. Calcium sulphide
B. Calcium carbide
C. Calcium carbonate
D. Calcium chloride
Answer» B. Calcium carbide
Explanation: Calcium carbide is used for artificially ripening fruit. When calcium carbide comes in contact with moisture, it produces acetylene gas, which is quite similar in reaction to the natural ripening agent ethylene. Acetylene acts like ethylene and accelerates the ripening process.

Which of the following is not a nitrogenous fetiliser?

A. Ammonium sulphate
B. Urea
C. Ammonium nitrate
D. Superphosphate
Answer» D. Superphosphate
Explanation: Superphosphateis a common synthetic phosphorus fertilizer. It contains phosphorus and sulphur in a ratio of 1 to 1.22. It is produced by treatment of "phosphate rock" with acids such as sulphuric acid. Superphosphate is the principal carrier of phosphate, the form of phosphorus usable by plants, and is one of the world's most important fertilizers.

Bauxite is used as raw material by which industry?

A. Aluminium
B. Iron
C. Steel
D. Gold
Answer» A. Aluminium
Explanation: Bauxite is the principal ore of aluminium. Bauxite is not a mineral. It is a rock formed from a laterite soil that has been severely leached of silica and other soluble materials in a wet tropical or subtropical climate. Aluminiumis extracted from bauxite using the Bayer process.

Which of the following is not a natural source of hydrocarbon?

A. Natural Gas
B. Coal
C. Petroleum
D. Mica
Answer» D. Mica
Explanation: There are three main natural sources of hydrocarbons: natural gas, petroleum and coal. Mica is a natural occurring mineral that is based on a collection of silicate minerals and composed of varying amounts of potassium, iron, aluminum, magnesium and water. It is widely used in the electrical industry.

An acid having basicity one is -

A. Sodium dihydrogen phosphate
B. Disodium hydrogen phosphate
C. Sodium phosphate
D. Phosphoric acid
Answer» B. Disodium hydrogen phosphate
Explanation: The basicity of an acid is the number of hydrogen ions (H+) which can be produced by the ionization of one molecule of the acid in aqueous solution. For ex-ample, the basicity of hydrochloric acid is 1 since one molecule of HCl produces one H+ ion in solution. Similarly, the basicity of Disodium phosphate (Na2HPO4) is one since it has one H+ displaceable ion.

Which one of the following vegetable oils is used in the manufacture of paints?

A. Palm oil
B. Sunflower oil
C. Linseed oil
D. Cottonseed oil
Answer» D. Cottonseed oil
Explanation: Linseed oil and castor oils are used mainly as drying agents in paints and varnishes. Linseed oil is generally used in the manufacture of oil paints, drying oil finish orvarnish in wood finishing, as a pigment binder in oil paints, as a plasticizer and in the manufacture of linoleum.

Dry ice is the solid form of :

A. Air 7
B. Carbon dioxide
C. Nitrogen
D. Water
Answer» B. Carbon dioxide
Explanation: Dry ice, sometimes referred to as "cardice," is the solid form of carbon dioxide. It is used primarily as a cooling agent. Its advantages include lower tem-perature than that of water ice and not leaving any residue. It is useful for preserving frozen foods, ice cream, etc., where mechanical cooling is unavailable.

The common name of sodium bicarbonate is -

A. Soda ash
B. Baking soda
C. Soda lime
D. Baking powder
Answer» B. Baking soda
Explanation: Sodium bicarbonate (NaHCO3) is also known as baking soda, bread soda, cooking soda, and bicarbonate of soda. It is primarily used in cooking (baking), as a leavening agent. It reacts with acidic, components in batters, releasing carbon dioxide, which causes expansion of the batter and forms the characteristic texture and grain in pancakes, cakes, quick breads, etc.

Which element behaves chemically both as metal and nonmetal?

A. Argon
B. Boron
C. Xenon
D. Carbon
Answer» B. Boron
Explanation: Some elements behave chemically both as metals and nonmetals, and are called metalloids. Their examples include Boron, Silicon, Germanium and Antimony.Elements which are neither metals nor non- metals are called Noble Gases.

The amount of oxygen in the atmosphere remains relatively constant because it is given off by -

A. Oceans
B. Animals
C. Rocks
D. Plants
Answer» D. Plants
Explanation: Just as water moves from the sky to the earth and back in the hydrologic cycle, oxygen is also cycled through the environment. Plants mark the beginning of the oxygen cycle. They use the energy of sunlight to convert carbon dioxide and water into carbohydrates and oxygen in a process called photosynthesis.

Which one of the following mineral does not contain oxygen?

A. Haematite
B. Bauxite
C. Cryolite
D. Calcite
Answer» C. Cryolite
Explanation: Cryolite (Na3AlF6, sodium hexafluoroaluminate) does not contain oxygen. It occurs as glassy, colorless, white-reddish to gray-black prismatic monoclinic crystals. Cryolite is used as an insecticide and a pesticide. It is also used to give fireworks a yellow color.

Biogas majorly contains?

A. Ethane
B. Methane
C. Hydrogen
Answer» B. Methane
Explanation: Biogas is a mixture of different gases, major portion in biogas being methane (CH4) and carbon dioxide (CO2). It also contains traces of other gases like hydrogen (H2), Moisture (H2O), hydrogen sulphide (H2S) etc.

The scientific name for common salt is-

A. Sodium hydroxide
B. Sodium chloride
C. Ammonium chloride
D. Sodium hydrogencarbonate
Answer» B. Sodium chloride
Explanation: Common salt is known as sodium chloride. It is an important raw material for various materials of daily use, such as sodium hydroxide, baking soda, washing soda etc.

Which of the following is a noble gas -

A. Argon
B. Hydrogen
C. Oxygen
D. Nitrogen
Answer» A. Argon
Explanation: Noble gas, any of the seven chemical elements that make up Group 18 (VIIIa) of the periodic table.

Permanent - hardness of water may be removed by addition of –

A. Alum
B. Sodium carbonate
C. Lime
D. Potassium Permangante
Answer» B. Sodium carbonate
Explanation: Sodium carbonate (also known as washing soda or soda ash) is a sodium salt of carbonic acid. In domestic use, it is used as a water softener in laundering. It competes with the magnesium and calcium ions in hard water and prevents them from bonding with the detergent being used. Sodium carbonate can be used to remove grease, oil and wine stains.

Which of the following is the best fuel in terms of energy released per gram of fuel?

A. Hydrogen
B. Methane
C. Ethanol
D. Butane
Answer» A. Hydrogen
Explanation: The amount of energy released increases with the number of bonds present in the chemical substance or fuel. That is because each bond has a certain amount of energy stored in it therefore the more bonds the more energy is stored and more energy is released if these bonds break through combustion. Theoretical values of

One carat of diamond is equal to -

A. 100mg
B. 150mg
C. 200mg
D. 250mg
Answer» C. 200mg
Explanation: One carat is equal to 200 milligrams, or in other words, a 5-carat stone weighs 1 gram. The weight of one carat is precisely 0.2 grams.

The manufacture of iron from iron ore involves the process of –

A. oxidation
B. reduction
C. fractional distillation
D. electrolysis
Answer» B. reduction
Explanation: The manufacture of iron ore involves the process of reduction. Important ores of iron : Haematite, Magnetite.

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

A. Eutrophication
B. Hardness
C. Alkalinity
D. Acidity
Answer» A. Eutrophication
Explanation: Higher concentration of Nitrogen and Phosphorus causes Eutrophication.

The smallest particle of an element is called -

A. Ion
B. Electron
C. Atom
D. Molecule
Answer» C. Atom
Explanation: An element is a substance completely made up of one atom. However, the atom itself is not the smallest known particle, but instead each atom is made up of three individual parts: electrons, protons and neutrons.

There are some substances whose odor changes in acidic or basic media. These are called -

A. Olfactory indicators
B. Litmus indicator
C. Gustatory indicators
D. All of the above
Answer» A. Olfactory indicators
Explanation: An Olfactory indicator is a substance whose smell varies depending on whether it is mixed with an acidic or basic solution. Onion , clove oil and vanilla extract are examples.

Which of the following elements has the atomic number greater than that of Phosphorus?

A. Aluminium
B. Silicon
C. Chlorine
D. Magnesium
Answer» C. Chlorine
Explanation: Chlorine is a chemical element with symbol Cl and atomic number 17. Phosphorus is a chemical element with symbol P and atomic number 15.

If the sewage is fully oxidized, the nitrogen is in the form of –

A. Nitrites
B. Ammonia
C. Nitramines
D. Nitrates
Answer» D. Nitrates
Explanation: Oxidized forms of nitrogen include nitrite (NO2) and nitrate (NO3). Nitrogen mainly occurs in wastewater in this form. Because nitrite is easily oxidized to nitrate, nitrate is the compound predominantly found in groundwater and surface waters.

Which among the following is used to dilute oxygen in the gas cylinders used by divers?

A. Krypton
B. Argon
C. Helium
D. Neon
Answer» C. Helium
Explanation: Helium is used to dilute the oxygen and nitrogen to reduce these affects. Helium is the gas of choice to use because it is an inert gas, is thinner, therefore more compressible than air, and its narcotic properties are negligible in comparison to nitrogen.

Which one of the following does not form oxyacid?

A. Sulphur
B. Chlorine
C. Nitrogen
D. Fluorine
Answer» D. Fluorine
Explanation: Fluorine cannot form oxyacid because fluorine is more electronegative than oxygen. For oxygen to bind, it must be a positively charged ion.

The gas used to extinguish fire is –

A. Neon
B. Nitrogen
C. Carbon dioxide
D. Carbon monoxide
Answer» C. Carbon dioxide
Explanation: Fires require these 3 things: a fuel (a hydrocarbon, which is a compound containing only carbon and hydrogen), a source of oxygen, and heal. Carbon Dioxide is most commonly used to extinguish fire as it displaces wwgen, thus choking the very source of a fire.

          is not an allotrope of carbon.

A. Buckminsterfullerene
B. Carbon Doxide
C. Diamond
D. Graphite
Answer» B. Carbon Doxide
Explanation: Carbon is capable of forming many allotropes due to its valency. Well-known forms of carbon include diamond and graphite. Other allotropes in clude: include buckyballs (fullerenes), amorphous carbon, glassy carbon, carbon nanofoam, nanotubes,and others.

Which hydrocarbons are the major constituents of 'LPG'?

A. Methane and Ethane
B. Propane and Butane
C. Pentane and Benzene
D. Only Methane
Answer» B. Propane and Butane
Explanation: Cooking gas, also known as Liquefied Petroleum Gas (LPG) is primarily propane (C3Hg) and butane (C4H10).

When cathode rays strike a target of high atomic weight, they give rise to –

A. α -rays
B. β and γ rays
C. X-rays
D. positive rays
Answer» C. X-rays
Explanation: When cathode rays strike a solid target of high atomic weight and high melting point such as tungsten, molybdenum, etc, they give rise to a highly pen-etrating radiation called the X-rays (LIT Physics by Dr. P.K Aganval).

The major use of sulphur is in the manufacture of –

A. H2SO4
B. H2S
C. SO2
D. Fungicide
Answer» A. H2SO4
Explanation: The major use of sulphur is in the manufacture of sulphuric acid (H2SO4) which is one of the most important compounds made by the chemical industry. It is used to make,literally, hundreds of compounds needed by almost every industry.

Which of the following will replace hydrogen from acids to form salts?

A. S
B. Na
C. Ag
D. P
Answer» B. Na
Explanation: All acids contain hydrogen atom (s). Dilute acids react with some metals such as Sodium, Potassium, Calcium, iron, etc to form salts. Sodium replaces two hydrogen atoms from Sulfuric acid (H2SO4) to form a normal salt, Sodium Sulphate (Na2SO4).

Which of the following metals has least, melting point?

A. Gold
B. Silver
C. Mercury
D. Copper
Answer» C. Mercury
Explanation: The melting point of the given metals (in Celsius) are:- Gold: 1063; Silver: 961; Copper: 1083; Mercury: 38.86. Mercury is the only elemental metal known to melt at a generally cold temperature.

Water gas is the combination of –

A. CO and H2
B. CO2 and H2
C. CO and H2O
D. CO2 and CO
Answer» A. CO and H2
Explanation: Water has is a synthesis gas, containing carbon monoxide (CO) and hydrogen has (H2). It is made by passing steam over a red- hot carbon fuel such as coke. The reaction between steam and hydrocarbons produce the has mixture.Q.21) Which of the following elements is

which is stable com- pound. This causes oxygen starvation in the body tissues and eventually causes death by suffocation.ammonium phosphate.

A. N4H6PO4
B. (NH4)3PO
C. (NH4)3PO4
D. (NH4)2PO4
Answer» C. (NH4)3PO4
Explanation: (NH4)3PO4 is a the chemical formula for ammonium phosphate. For more chemistry related queries log on to website world of chemicals.

If there is one million Mg2+ ions in MgCl2, how many chloride ions are there?

A. Two million
B. One million
C. Half a million
D. Ten million
Answer» A. Two million
Explanation: 0

The gas that causes suffocation and death when coal or coke is burnt in a closed room is -

A. Methane
B. Ethane
C. Carbon monoxide
D. Carbon dioxide
Answer» C. Carbon monoxide
Explanation: Exhaust fumes of motor cars, gases produced, from coal fire in a closed room and coal gas, all contain carbon monoxide, which is the cause of their poisonous nature. When carbon monoxide is inhaled, it prevents the oxygen from combining with hemoglobin and instead combines itself with hemoglobin to form carboxyhaemoglobin,

Teryleneisa condensation polymer of ethylene glycol and which acid?

A. Benzoic Acid
B. Salicylic acid
C. Phthalic acid
D. Terephthalic acid
Answer» D. Terephthalic acid
Explanation: Terylene is a co-polymer of ethylene glycol and Terephthalic acid. Also known as Dacron, it is prepared by the condensation polymerization of ethylene glycerol and. Terephthalic acid with elimination of water. The reaction is carried out at about 420- 460 K in the presence of a catalyst consisting of a mixture of zinc acetate and antimony trioxide.

Which of the following ores does not contain iron?

A. Haematite
B. Magnetite
C. Limonite
D. Cassiterite
Answer» D. Cassiterite
Explanation: 0

Acids generate:

A. Acids generate hydrogen ions.
B. Bases generate hydroxide ions.
C. Both are correct
D. Both are incorrect
Answer» C. Both are correct
Explanation: Acids, in presence of water, give hydrogen ions (H+). Similarly, bases generate hydroxide (OH-) ions in water.

Which one of the following is not a characteristic feature of alloys? They are –

A. Compounds
B. Mixtures
C. Solutions
D. Homogeneous systems
Answer» D. Homogeneous systems
Explanation: An alloy is a mixture or metallic solid solution composed of two or more elements. So they are heterogeneous systems. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal (heat treatment) history. Alloys usually have different properties from those of the component elements.

When iron rusts, its weight –

A. decreases
B. increases
C. remains the same
D. first increases and then decreases
Answer» B. increases
Explanation: When iron rusts, oxide compounds are formed due the interaction between oxygen in the air or in water and the metal. Because of the oxygen atoms binding with the metal, the weight of the metal with rust will increase.

Nylon threads are made of -

A. Polyester polymer
B. Polyamide polymer
C. Polyvinyl polymer
D. Polysaccharide
Answer» B. Polyamide polymer
Explanation: Nylon is a generic designation for

The manufacturing of iron from ironore involves the process of -

A. Oxidation
B. Reduction
C. Electrolysis
D. Fractional distillation
Answer» B. Reduction
Explanation: Iron is extracted from iron ore in a huge container called a blast furnace. Iron ores such as hematite contain iron oxide. The oxygen must be removed from the iron oxide to leave the iron behind. Reactions in which oxygen is removed are called reduction reactions.

Which one of the following elements is metalloid?

A. Si
B. Pb
C. Ge
D. C
Answer» C. Ge
Explanation: A metalloid is a chemical element with properties in between metals and nonmetals. Germanium (Ge) is a chemical element. It is a lustrous, hard, grayish-white metalloid in the carbon group.

Cobalt (60) isotope is used in the treatment of which disease?

A. Heart diseases
B. cancer
C. diabetes
D. skin diseases
Answer» B. cancer
Explanation: In cobalt-60 therapy, cobalt-60- generated gamma radiation is used to destroy tumors. Cobalt-60 therapy is also known as Gamma Knife® therapy.

Which one of the following is used in the preparation of antiseptic solution?

A. Potassium nitrate
B. Iodine
C. Iodine chloride
D. Potassium chloride
Answer» B. Iodine
Explanation: Antiseptics are chemical agents that slow or stop the growth of micro-organisms (germs) on external surfaces of the body and help prevent infections.

The characteristic odour of garlic is due to -

A. a chloro compound
B. a sulphur compound
C. a fluorine compound
D. acetic acid
Answer» B. a sulphur compound
Explanation: The sulfur compounds in onions and garlic are called sulfites. These highly irritating chemicals can kill microbes and repel insects; prolonged contact with garlic will even blister the skin.

An emulsion is a colloidal solution of -

A. Liquid in liquid
B. Solid in liquid
C. Gas in solid
D. Solid in Solid
Answer» A. Liquid in liquid
Explanation: An emulsion is a mixture of two or more liquids that are normally immiscible (unmixable or unblendable). Emulsions are part of a more general class of two-phase systems of matter called colloids. Examples of emulsions include vinaigrettes, homogenized milk, mayonnaise, and some cutting fluids for metal working.

              is a by product of sewage treatment and can be decomposed to produce biogas.

A. Sewage
B. Sludge
C. Sewer
D. Scum
Answer» B. Sludge
Explanation: Sludge refers to the residual, semi-solid material that is produced as a by- product during sewage treatment of industrial or municipal wastewater. It can be used to produce biogas through a process called anaerobic digestion or fermentation.

Silver gets corroded due to               in air.

A. Oxygen
B. Hydrogen Sulphide
C. Carbon dioxide
D. Nitrogen
Answer» B. Hydrogen Sulphide
Explanation: Silver is a fairly stable metal and under normal circumstances does not corrode quickly. However, it is particularly susceptible to the effects of the sulfide radical. However, when exposed to air, silver reacts with Hydrogen Sulphide in the atmosphere, especially in marine environment, and readily forms a surface tarnish of silver sulphide.

Which of the following is a radioactive element?

A. Cobalt
B. Uranium
C. Argon
D. Chromium
Answer» B. Uranium
Explanation: Uranium (U) is a naturally occurring radioactive element. Its nucleus is unstable, so the element is in a constant state of decay, seeking a more stable arrangement. One of its isotopes, uranium-235, is the only naturally occurring isotope capable of sustaining a nuclear

Whatis Zeolite?

A. Hydrated Aluminosilicate
B. Hydrated Calcium Sulphate
C. Dehydrated Aluminosilicate
D. Dehydrated Calcium Sulphate
Answer» A. Hydrated Aluminosilicate
Explanation: Zeolites are hydrated aluminosilicate minerals made from interlinked tetrahedra of alumina (AlO4) and silica (SiO4). In simpler words, they're solids with a relatively open, three-dimensional crystal structure built from the elements aluminium, oxygen, and silicon, with alkali or alkaline-Earth metals (such as sodium, potassium, and magnesium) plus water molecules trapped in the gaps between them.

L.P.G. is mostly liquefied

A. hydrogen
B. Oxygen
C. butane
D. methane
Answer» C. butane
Explanation: Liquefied petroleum gas or liquid petroleum gas (LPG) is mostly propane (C3H8), or butane (C4H10). They are most commonly mixtures of these two hydrocarbon gases that are used as fuel in heating appliances, cooking equipment, and vehicles. In the northern hemisphere winter, the mixes contain more propane, while in summer, they contain more butane.

Which have the maximum density?

A. Water
B. Benzene
C. Ice
D. Chloroform
Answer» A. Water
Explanation: Water has its maximum density of 1g/cm3 at 4 degrees Celsius. When the temperature changes from either greater or lessthan 4 degrees, the density will become less than 1 g/cm3.

Which of the following metals is stored in kerosene oil?

A. Platinum
B. Copper
C. Sodium
D. Gold
Answer» C. Sodium
Explanation: Owing to its extreme reactivity, sodium occurs in nature only combined in compounds never as a pure elemental metal.

Atoms having the same number of protons but different number of neutrons are called :

A. Isotopes
B. Cations
C. Higgs-boson
D. Anions .
Answer» A. Isotopes
Explanation: Atoms that have the same number of protons but different numbers of neutrons are called isotopes. For example, carbon-12, carbon-13 and carbon-14 are three isotopes of the element carbon with mass numbers 12, 13 and 14 respectively. The atomic number of carbon is 6, which means that every carbon atom has 6 protons, so that the neutron numbers of these isotopes are 6, 7 and 8 respectively.

Which one of the following elements is least likely to be found in commercial fertilisers?

A. Nitrogen
B. Phosphorus
C. Potassium
D. Silicon
Answer» D. Silicon
Explanation: Commercial Fertilizers - a substance containing one or more recognized plant nutrients and that is used for its plant nutrient content or that is designated for use or claimed to have value in promoting plant growth.

Organic compounds are -

A. Covalent compounds
B. Ionic compounds
C. Co-ordination compounds
D. Interstitial compounds
Answer» A. Covalent compounds
Explanation: Organic compounds are always covalent compounds because it is more energetically favorable for carbon to covalently bond. Organic compounds, such as carbohydrates, lipids, proteins and nucleic acids, are all examples of covalent compounds.

Which of the following is NOT a renewable source of energy?

A. Wind energy
B. Geothermal energy
C. Energy from fossils
D. Solar energy
Answer» C. Energy from fossils
Explanation: Renewable energy is energy that is collected from renewable resources, which are naturally replenished on a human timescale, such as sunlight wind, rain, tides, waves, and geothermal heat.

Compounds of carbon having double or triple bonds between their carbon atoms are called

A. Saturated compounds
B. Unsaturated compounds
C. Reactive compounds
D. None of the above
Answer» B. Unsaturated compounds
Explanation: Compounds of carbon, which are linked by only single bonds between the carbon atoms are called saturated compounds. Compounds of carbon having double or triple bonds between their carbon atoms are called unsaturated compounds.

An alloy used in making heating elements for electric heating device is -

A. Solder
B. Alloy Steel
C. Nichrome
D. German Silver
Answer» C. Nichrome
Explanation: Nichrome is a mixture of chromium and nickel. Nichrome wire is a great conductor of electricity. Nichrome is used to make heating coils and other types of elements in household appliances.

The degree of dissociation of an electrolyte depends on -

A. dilution
B. impurities
C. atmospheric pressure
D. method of dissolution
Answer» A. dilution
Explanation: The extent to which an electrolyte dissociates into ions is known as degree of dissociation or ionization and depends upon the following factors: (1) Nature of the electrolyte,(2) Temperature, (3) Dilution, (4) nature of the solvent, and (e) presence of other ions.

Which of the following is present in Nail polish remover?

A. Citric acid
B. Acetone
C. Ethylene
D. Benzene
Answer» B. Acetone
Explanation: Acetone can also remove artificial nails made of acrylic or cured gel. An alternative nail polish remover is ethyl acetate, which often also contains isopropyl alcohol.

Glass is mainly composed of -

A. Sodium silicate
B. Calcium carbonate
C. Calcium hydroxide
D. Sodium bicarbonate
Answer» A. Sodium silicate
Explanation: Glass is made from silica (SiO₂) and soda lime, which react to form sodium silicate.

Which of the following is essential for the synthesis of thyroxin?

A. Potassium
B. Sodium
C. Calcium
D. Iodine
Answer» D. Iodine
Explanation: Iodine is essential for the synthesis of Thyroxine, one of the two major hormones secreted by the thyroid gland. Thyroxine is formed by the molecular addition of iodine to the amino acid tyrosine while the latter is bound to the protein thyroglobulin.

Chlorophyll is porphyrin containing -

A. magnesium
B. iron
C. calcium
D. (4) tin
Answer» A. magnesium
Explanation: Chlorophyll are greenish pigment which contain a porphyrin ring. This is a stable ring-shaped molecule around which electrons are free to migrate. Magnesium is central atom in porphyrin structure of chlorophyll.

Which of the following processes is used for the production of Biodiesel?

A. Transamination
B. Transcription
C. Transesterification
D. Translation
Answer» C. Transesterification
Explanation: Biodiesel production is the process of producing the biofuel, biodiesel, through the chemical reactions trans- esterification and esterification. This involves vegetable or animal fats and oils being reacted with short-chain alcohols (typically methanol or ethanol).

A matured mammalian cell without nucleus is –

A. Lymphocyte
B. Erythrocyte
C. Spermatozoan
D. Oocyte
Answer» B. Erythrocyte
Explanation: Mammalian erythrocytes are unique among the vertebrates as they are non- nucleated cells in their mature form. These cells have nuclei during early phases of erythropoiesis, but extrude them during development as they mature in order to provide more space for hemoglobin. In mammals, erythrocytes also lose all other cellular organelles such as their mitochondria, Golgi apparatus and endoplasmic reticulum.

The most common cause of pollution of air is –

A. Carbon dioxide
B. Carbon monoxide
C. Sulphur dioxide
D. Smoke
Answer» C. Sulphur dioxide
Explanation: The most common sources of air pollution include particulates, ozone, nitrogen dioxide, and sulfur dioxide. The largest sources of SO2 emissions are from fossil fuel combustion at power plants (73%) and other industrial facilities (20%). Smaller sources of SO2 emissions include industrial processes such as extracting metal from ore, and the burning of high sulfur containing fuels by locomotives, large ships, and non-road equipment. It is linked with a number of adverse effects on the respiratory system.

The main source of carbon monoxide is

A. Industrial process
B. Fuel combustion
C. Transportation
D. Solid waste disposal
Answer» C. Transportation
Explanation: The main source of carbon monoxide is burning of fossil fuel

Tooth enamel is the hardest substance found in the human body. What is it made up of -

A. Calcium carbonate
B. Limestone
C. Calcium phosphate
D. Calcium fluoride
Answer» C. Calcium phosphate
Explanation: The protective layer around your teeth, called enamel, is the strongest substance that our body produces. In fact, tooth enamel is stronger than any other substance on earth except for diamonds.

A solution turns blue litmus red, its pH is likely to be -

A. 11
B. 9
C. 5
D. 10
Answer» C. 5
Explanation: If the litmus paper turns red, it indicates the presence of an acid while if it turns blue, it indicates the presence of a base.

Which of the following metals is used in Space Crafts to withstand high temperatures?

A. Fe
B. Ti
C. Ni
D. Pb
Answer» B. Ti
Explanation: Titanium alloy, which has high corrosion resistance, high specific strength, and good heat resistance, is used for different spacecraft parts including outer fuel tank sheathing and wings. It is extremely strong at high temperatures.

Brass gets discoloured in air due to constant exposure in presence of:

A. Aluminium phosphide
B. Hydrogen sulphide
C. Hydrogenated wafers
D. Aluminium sulphide
Answer» B. Hydrogen sulphide
Explanation: Brass gets discoloured in air because of Hydrogen sulphide. Transition elements are coloured. The brass is combination of Zn and Cu. But it is discoloured due to hydrogen sulphide in air.

Neutrons are slowed down in a nuclear reactor by –

A. Fissionable Material
B. Moderator
C. Control rods
D. Cooling system
Answer» B. Moderator
Explanation: In thermal nuclear reactors, the coolant acts as a moderator that must slow down the neutrons before they can be efficiently absorbed by the fuel. It allows neutrons to slow down to energies where they can easily cause a nucleus to fission.

An element of atomic no. 29 belongs to

A. s-block
B. d-block
C. p-block
D. f-block
Answer» B. d-block
Explanation: Copper (Cu) has the atomic number of 29. Copper belongs to the d-block which is the collective name for Groups 3 to 12 in the periodic table. Most of the d-block elements are considered to be metals, with a common lustrous metallic appearance.

Mechanical energy is the combination of kinetic energy and               .

A. Heat energy
B. Chemical energy
C. Potential energy
D. Nuclear energy
Answer» C. Potential energy
Explanation: Mechanical energy is the energy possessed by an object due to either its motion or its stored energy of position. The total amount of mechanical energy is merely the sum of potential energy and kinetic energy.

Magnetism at the centre of a bar magnet is -

A. minimum
B. maximum
C. zero
D. minimum or maximum
Answer» C. zero
Explanation: The field at the center is not zero, but weak. At the exact center of a magnet thefield lines are parallel (straight lines if we draw it). Anywhere else they are slightly divergent.

Substances that cause a reaction to occur or proceed at a different rate without the reaction itself being affected are called -

A. Catalysts
B. Hydrocarbons
C. Oxidising agents
D. Substitutes
Answer» A. Catalysts
Explanation: Catalysts are substances that cause a reaction to occur or proceed at a different rate without the reaction itself being affected. Eg: hydrogenation of vegetable oils using a nickel catalyst.

Which one of the following elements exhibits the greatest tendency to lose electrons?

A. Fluorine
B. Lithium
C. Oxygen
D. Zine
Answer» B. Lithium
Explanation: Alkali metals such as Lithium are the most electropositive elements in the periodic table. As alkali metals have low ionization energies, they have a great tendency to lose electrons forming unipositive ions.

Poison used for killing rats is –

A. Calcium phosphide (Ca3P2)
B. Zinc phosphide (Zn3P2)
C. Magnesium nitride (Mg3N2)
D. Magnesium phosphide (Mg3P2)
Answer» B. Zinc phosphide (Zn3P2)
Explanation: Zinc phosphide is an inorganic compound that is used in pesticide products as a rodenticide. Formulated as attractive bait, it releases phosphine gas once it is exposed to acid and moisture in the stomach. The phosphine gas is very toxic to all animals.

The commonly used safety fuse-wire is made of -

A. an alloy of Nickel and Lead
B. an alloy of Tin and Lead
C. an alloy of Tin and Nickel
D. an alloy of Lead and Iron
Answer» B. an alloy of Tin and Lead
Explanation: As a rule, fuse elements of time delay fuses contain low melting point materials, e.g. tin (Sn) or zinc (Zn) and alloys thereof.

Lead pencil contains -

A. Lead nitrate
B. Graphite
C. Lead peroxide
D. Lead Sulphate
Answer» B. Graphite
Explanation: Most pencil cores are made of graphite mixed with a clay binder which leaves grey or black marks that can be easily erased.

The most suitable unit for expressing nuclear radius is -

A. nanometre
B. fermi
C. angstrom
D. micron
Answer» B. fermi
Explanation: The atomic radius is a measure of the size of an atom. It is defined as one half the distance between the nuclei of two identical atoms that are bonded together. Angstrom is the most common unit used for measuring atomic radius.

The catalyst used in hydrogenation of oils is -

A. Fe
B. V2O5
C. Ni
D. O2
Answer» C. Ni
Explanation: The catalyst used in hydrogenation of oils is nickel. It is used to speed up the reaction. Vegetable oils convert into vanaspati after hydrogenation.

What is used in storage batteries?

A. Copper
B. Tin
C. Lead
D. Zinc
Answer» C. Lead
Explanation: The electrodes of the cells in a storage battery consist of lead grids. The openings of the anodic grid is filled with spongy (porous) lead. The openings of the cathodic grid is filled with lead dioxide (PbO2). Dilute sulfuric acid (H2SO4) serves as the electrolyte. Lead-acid batteries, also known as lead' storage batteries, can store a lot of charge and provide high current for short periods of time.

The biogas used for cooking is a mixture of which of the following?

A. Carbon dioxide and oxygen
B. Isobutane and propane
C. Methane and Carbon monoxide
D. Methane and carbon dioxide
Answer» D. Methane and carbon dioxide
Explanation: Biogas is essentially a mixture of Methane (CH4, around 55-75%) but also contains Carbon Dioxide (CO3), around 25- 30%), varying quantities of Water (H2O) and Hydrogen Sulphide (H2S). Other compounds can also be found, especially in waste dump biogas: Ammonia (NH3), Hydrogen (H2), Nitrogen (N2) and Carbon Monoxide (CO). Methane is the valuable component under the aspect of using biogas fuel.

Ozone saves the biosphere by absorbing high energy radiations called -

A. Infra-red
B. Gamma rays
C. Ultraviolet rays (UV)
D. X-rays
Answer» C. Ultraviolet rays (UV)
Explanation: The ozone layer or ozone shield is a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet (UV) radiation. It absorbs 97 to 99 percent of the Suns medium-frequency ultraviolet light (from about 200 nm to 315 nm wavelength), which otherwise would potentially damage exposed life forms near the surface.

Silica gel is a -

A. moisturizer
B. flavouring agent
C. drying agent
D. delicious food
Answer» C. drying agent
Explanation: Silica gel is a drying agent, meant to remove moisture from an enclosed space. It is a granular, vitreous, porous form of silicon dioxide made synthetically from sodium silicate. Silica gel packs are found in boxes containing electronics or new shoes and inside purses or medicine bottles. The packets contain either granular silicic acid, which resembles sand, or tiny gel beads.

Neutron was discovered by -

A. Chadwick
B. Rutherford
C. Fermi
D. Bohr
Answer» A. Chadwick
Explanation: Neutron was discovered by James Chadwick in the year 1932. The neutron is a subatomic particle, symbol n or n⁰, with no net electric charge and a mass slightly larger than that of a proton. Protons and neutrons constitute the nuclei of atoms.

Iodine can be separated from a mixture of Iodine and Potassium Chloride by -

A. Filtration
B. Sublimation
C. Distillation
D. Sedimentation
Answer» B. Sublimation
Explanation: Iodine can be separated from a mixture of Iodine and Potassium Chloride by Sublimation. Sublimation is the transition of a substance directly from the solid to the gas phase, without passing through the intermediate liquid phase.

Which of the following produces H2 gas, when reacts with acid?

A. Zn
B. S
C. C
D. O
Answer» A. Zn
Explanation: As, Zinc is a metal so it will produce H2 gas when reacts with acid. Active metals react with acids to produce hydrogen because they are above hydrogen in the activity series.

Which one of the following is commonly used for pulp bleaching in the paper industry?

A. Mild sulphuric acid
B. Glucose isomerase
C. Hydrogen peroxide
D. Iodine and water
Answer» C. Hydrogen peroxide
Explanation: Bleaching of wood pulp is the chemical processing carried out to decrease the color of the pulp, so that it becomes whiter. Alkaline hydrogen peroxide is the most commonly used bleaching agent for mechanical pulp. It selectively oxidizes non-aromatic conjugated groups responsible for absorbing visible light. The decomposition of hydrogen peroxide is catalyzed by transition metals.

Biofertilizers convert nitrogen to

A. nitrates
B. ammonia
C. nitrogenase
D. amino acids
Answer» B. ammonia
Explanation: Bio-fertilizers are micro- organisms which bring about nutrientenrichment of soil by enhancing the availability of nutrients to crops. The micro-organisms which act as bio-fertilizers are bacteria, cyanobacteria (blue green algae) and mycorrhizal fungi. The symbiotic nitrogen- fixing bacteria convert free nitrogen to ammonia, which the host plant utilizes for its development.

Radioactivity was discovered by

A. J.J. Thomson
B. W.Roentgen
C. H.Becquerel
D. M. Curie
Answer» C. H.Becquerel
Explanation: Antoine-Henri Becquerel is known for his discovery of radioactivity, for which he received the Nobel Prize for Physics in 1903. Unstable atomic nuclei will spontaneously decompose to form nuclei with a higher stability.

Which one of the following can be oxidized to the corresponding carbonyl compound -

A. O-Nitrophenol
B. Phenol
C. 2-methyl-2-hydroxy propane
D. 2-hydroxy propane
Answer» D. 2-hydroxy propane
Explanation: 0

             gives hardness to stainless steel.

A. Zinc
B. Lead
C. Carbon
D. Tin
Answer» C. Carbon
Explanation: Iron is alloyed with carbon lo make steel and has the effect of increasing the hardness and strength of iron. Pure iron cannot be hardened or strengthened by heat treatment but the addition of carbon enables a wide range of hardness and strength. High-carbon stainless steel contains a minimum of 0.3% carbon. The higher the carbon content, the less formable and the tougher the steel becomes.

Which of the following is not soluble in water?

A. Lead Sulphate
B. Zinc sulphate
C. Potassium sulphate
D. Sodium sulphate
Answer» B. Zinc sulphate
Explanation: Lead sulfate (PbSO4) is a white crystalline solid. It is insoluble in water and sinks in it. It is often seen in the plates/electrodes of car batteries, as it is formed when the battery is discharged. It is also known as fast white, milk white, sulfuric acid lead salt or anglesite.
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