1240+ Chemistry Solved MCQs

1001.

In a freezer ice cubes will be formed more quickly in trays made of -

A. rubber
B. plastic
C. aluminium
D. wood
Answer» C. aluminium
Explanation: Aluminium being a good conductor of heat conducts away the heat from the substance quite easily and causes quick freezing.
1002.

Who discovered X-rays?

A. W. C. Roentgen
B. Albert Einstein
C. Samuel Cohen
D. Edward Taylor
Answer» A. W. C. Roentgen
Explanation: X-rays were discovered by Wilhelm Conrad Roentgen, a Professor at Wuerzburg University in Germany, on 8 November 1895.
1003.

The important metal used with iron to produce stainless steel is –

A. Al
B. Chromium
C. Tin
D. Carbon
Answer» B. Chromium
Explanation: Stainless steel is an alloy of iron with chromium. Chromium prevents its from corrosion. Stainless steel differs from carbon steel by the amount of chromium present.
1004.

Which of the following is an Inert Gas?

A. Hydrogen
B. Nitrogen
C. Oxygen
D. Argon
Answer» D. Argon
Explanation: Argon is an inert gas (noble gas) that is placed in Group 18 of the periodic table. It is the most abundant noble gas in Earth's crust, comprising 20.00015% of the crust. Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Rn) are other noble gases that occur naturally.
1005.

Which one of the following metals does not form amalgam?

A. Zinc
B. Copper
C. Magnesium
D. Iron
Answer» D. Iron
Explanation: The definition of an amalgam is a mixture of metals and mercury, which can be man-made or can be naturally occurring.
1006.

Ozone layer in the upper parts of the atmosphere serves as a protective shield against harmful

A. solar ultraviolet radiation
B. solar infrared radiation
C. CO2 in the air
D. SO2 in the air
Answer» A. solar ultraviolet radiation
Explanation: Ozone layer serves as a protective shield against harmful solar ultraviolet radiation.
1007.

Which of the following is Colourless?

A. Chlorine
B. Oxygen
C. Phosphorus
D. Sulphur
Answer» B. Oxygen
Explanation: 0
1008.

The two metal ions that cause hardness to water are:

A. Calcium, Magnesium
B. Sodium, Calcium
C. Sodium, Potassium
D. Sodium, Magnesium
Answer» A. Calcium, Magnesium
Explanation: Calcium and magnesium ion cause hardness of water.
1009.

The liquid waste from kitchens and baths, of residences is known as:

A. Domestic sewage
B. Storm water
C. Sullage
D. Refuse
Answer» C. Sullage
Explanation: The liquid waste from kitchens and baths, of residence is known as sullage.
1010.

Which one of the following is an example of a gel?

A. Cheese
B. Milk
C. Face cream
D. Shaving cream
Answer» C. Face cream
Explanation: A gel is a solid, jelly-like material that can have properties ranging from soft and weak to hard and tough. Gels consist of a solid three-dimensional network that spans the volume of a liquid medium and ensnares it through surface tension effects. Shaving creams in a can are commonly dispensed as a foam or a gel.
1011.

Quartz is made of –

A. Calcium Sulphate
B. Calcium Silicate
C. Sodium Sulphate
D. Sodium Silicate
Answer» D. Sodium Silicate
Explanation: Quartz is an abundant mineral in the Earth's continental crust. It is made tip of a continuous framework of SiO4 silicon-oxygen tetrahedra, wit Ii each oxygen being shared between two tetrahedra, giving an overall formula SiO2.
1012.

Which among the following coal contains 90 per cent of carbon?

A. Anthracite
B. Bitumen
C. Lignite
D. Peat
Answer» A. Anthracite
Explanation: Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded asmetamorphic rock because of later exposure to elevated temperature and pressure. Coal is composed primarily of carbon along with variable quantities of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Anthracite contains 90 per cent of carbon.
1013.

Eposure to mixtures of chemicals are greater than expected on the basis of effects of expo-sure to each chemical individually. This is known as –

A. Additives
B. Antagonism
C. Synergism
D. Independent
Answer» C. Synergism
Explanation: When the toxic effect of the mixture is greater than that expected for the sum of individual constituent doses, which is that effects of combined doses are more-than- additive, the interactions are said to be synergistic. Conversely, when the toxic effect of the mixture is less than that expected under the dose additivity assumption, the interactions are said to be antagonistic.
1014.

The filter over which sewage is sprinkled is called as –

A. Trickling filter
B. Percolating filter
C. Contact bed
D. Intermittent sand filter
Answer» A. Trickling filter
Explanation: A trickling filter, also known as percolating filter, is an artificial bed of stone or broken brick material over which waste water or sewage is allowed to sprinkle or to trickle. It is then collected through the under drainage system.
1015.

Which of the following is an iron ore?

A. Bauxite
B. Magnetite
C. Lignite
D. Nitrite
Answer» B. Magnetite
Explanation: Magnetite is a 'mineral, one of the two common naturally occurring oxides of Iron. It is the most magnetic of all the naturally occurring minerals on Earth.
1016.

Iodine value is used to estimate –

A. Hydroxyl groups in oil
B. Alkali, content in oil
C. Unsaturation in oil
D. Carboxylic groups in oil
Answer» C. Unsaturation in oil
Explanation: Iodine value is used to estimate unsatwation in oil.
1017.

Element 106 was discovered by –

A. Rutherford
B. Seaborg
C. Lawrence
D. Kurchatove
Answer» B. Seaborg
Explanation: Element 106 was discovered by Seaborg.
1018.

Milk of magnesia is an example of a/an

A. Acid
B. Base
C. Salt
D. None of the above
Answer» B. Base
Explanation: Milk of Magnesia or Magnesium hydrozide is a base and an antacid. During indigestion, the stomach produces too much acidand this causes pain and irritation. To get rid of this pain, people use bases called antacids.
1019.

A bee-sting leaves an acid which causes pain and irritation.

A. The injected acid is -
B. acetic acid
C. sulphuric acid
D. citric acid
Answer» D. citric acid
Explanation: Formic acid (systematically called methanoic acid) is the simplest carboxylic acid. Its formula is CH2O2 or HCOOH.
1020.

Earth's atmosphere is an envelope of gases extending to a height of –

A. 100 km
B. 150 km
C. 200 km
D. 300 km
Answer» C. 200 km
Explanation: The atmosphere of the. Earth is an envelope of gases extending to a height of 200km.
1021.

In its reaction with silver nitrate, C2H2 shows –

A. Oxidising property
B. Reducing property
C. Basic property
D. Acidic property
Answer» D. Acidic property
Explanation: When treated with ammoniacal silver nitrate solution alkynes form white precipitate of silver acetylides.
1022.

Iron is extracted from -

A. Cinnabar
B. Haematite
C. Bauxite
D. Dolomite
Answer» B. Haematite
Explanation: Haematite is mined as the main ore of iron. It is harder than pure iron, but much more brittle. It is coloured black to steel or silver-gray, brown to reddish brown, or red.
1023.

Which of the following imparts a blue colour to glass?

A. Cobalt oxide
B. Copper oxide
C. Iron oxide
D. Nickel oxide
Answer» A. Cobalt oxide
Explanation: The addition of oxides, sulfides, salts, and other compounds of different metals to molten glass at the time of manufacture adds colour to glass. The introduction of electrically charged ions which are evenly distributed in the glass during manufacture also gives glass a characteristic colour. Cobalt oxide: deep blue colour; copper oxide: turquoise; chromium: dark green to black; cadmium sulfide: deep yellow, etc.
1024.

Of the following, which one pol-lutes the air of a big City?

A. Copper
B. Chromium
C. Lead
D. Cadmium
Answer» C. Lead
Explanation: The most common source of lead air pollution is from metal processing, but there are other manufacturing and industry sources as well. The highest lead air pollution levels are found near battery manufacturing and iron and other metal producing plants. Lead air pollution is a dangerous form of pollution because of the way lead builds up in our bodies.
1025.

Wood spirit is –

A. Methyl alcohol
B. Ethyl alcohol
C. Butyl alcohol
D. Propyl alcohol
Answer» A. Methyl alcohol
Explanation: Methanol is also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits. It acquired the name "wood alcohol" because it was once produced chiefly as a byproduct of the destructive distillation of wood. Modern methanol is produced in a catalytic industrial process directly from carbon monoxide, carbon dioxide, and hydrogen.
1026.

Which one of the following petroleum refinery products has the lowest boiling point?

A. Kerosene
B. Gasoline
C. Diesel
D. Lubricating oil
Answer» D. Lubricating oil
Explanation: Lubricating oil is the most commonly used lubricant because of its wide range of possible applications. The two basic categories of lube oil are mineral and synthetic.
1027.

Liquid metal is -

A. Mercury
B. Sodium
C. Antimony
D. None
Answer» A. Mercury
Explanation: Liquid metal consists of gallium- containing alloys with very low melting points which are liquid at room temperature. The standard metal formerly is mercury.
1028.

Which of the following is used for removing air bubbles from glass during its manufacture?

A. Fledspar
B. Arsenic oxide
C. Potassium Carbonate
D. Soda Ash
Answer» B. Arsenic oxide
Explanation: 0
1029.

The fat of a common mussel-secretes a sticky glue that can be used to make heart implants. The unique chemical compound present in the glue is:

A. Amino phenyl alanine
B. Hydroxy phenyl alanine
C. Phenyl alanine
D. Dihydroxy phenyl alanine
Answer» D. Dihydroxy phenyl alanine
Explanation: The foot of the common mussel (Mytilus edulis) produces a sticky glue due to a unique compound called mussel adhesive protein, which contains a high concentration of an amino acid, DOPA (dihydroxyphenylalanine), which can cling to wet surfaces with extraordinary strength. Besides heart implants, the compound could be used as a tooth coating to prevent dental plaque, which is caused by bacterial infection.
1030.

Nitrogen is an essential constituent of all:

A. Fats
B. Proteins
C. Vitamins
D. Carbohydrates
Answer» B. Proteins
Explanation: Nitrogen is a major constituent of all proteins, and thus of all living organisms. The deficiency of nitrogen causes yellowing of older leaves, stunted plants, dormancy of lateral buds, purple colouration in shoot axis surface, wrinkling of cereal grains and inhibition of cell division.
1031.

Thissubstance is commonly used in the kitchen for making tasty crispy pakoras and is sometimes added for faster cooking. Which of the following is it?

A. Baking soda
B. Bleaching powder
C. Vinegar
D. Artificial sweeteners
Answer» A. Baking soda
Explanation: Baking soda. When mixed with an acid, baking soda spurs a chemical reaction that produces carbon dioxide gas—or put more simply, it creates bubbles that cause baked goods to rise.
1032.

Ferrous sulphate is used in water treatment as a/an -

A. Oxidizing agent
B. Reducing agent
C. Coagulant aid
D. Adsorbent
Answer» C. Coagulant aid
Explanation: 0
1033.

Philosopher's Wool is -

A. Zinc carbonate
B. Zinc sulphate
C. Zinc oxide
D. Zinc blende
Answer» C. Zinc oxide
Explanation: Philosopher's wool is chemically zinc oxide.
1034.

The process by which milk is converted to curd is called –

A. Pasteurization
B. Vernalization
C. Fermentation
D. Retting
Answer» C. Fermentation
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. In Asia, curds are essentially a vegetarian preparation using yeast to ferment the milk.
1035.

The technique of calculating the age of fossil organisms is -

A. Radiocarbon dating
B. Electroporation
C. Counting the annual rings
D. Micromanipulation
Answer» A. Radiocarbon dating
Explanation: Radiocarbon dating (usually referred to as simply carbon dating) is a radiometric dating method that uses the naturally occurring radioisotope carbon-14 (14C) to estimate the age of carbon-bearing materials up to about 58,000 to 62,000 years. The technique of radiocarbon dating was developed by Willard Libby and his colleagues at the University of Chicago in 1949.
1036.

Of the following which one pollutes the air of a big city?

A. Copper
B. Chromium
C. Lead
D. Calcium
Answer» C. Lead
Explanation: Lead pollution primarily came from cars in the past. Today, lead pollution primarily comes from lead smelters, metal processing plants and incinerators. Deposits of lead in soil can harm both humans and animals by absorbing it into a body.
1037.

"Fire-fighting clothes" are made from

A. Mica
B. Asbestos
C. Talc
D. Steatite
Answer» B. Asbestos
Explanation: Bunker Gear or "Turnout Gear" are terms used by many firefighters to refer to their system of outer protective clothing. Fire fighter used to be made of asbestos in the past. Because of its carcinogenic properties and other harmful effects, it has slowly been replaced by other substitutes. Fire-fighting and working clothes and accessories for firemen, rescuers and industrials made of materials FR cotton, Nomex, Modacryl, FR viscose and others.
1038.

Hydrofluoric acid is not kept in glass bottles because it reacts with -

A. visible light
B. silicon dioxide of glass
C. aluminium oxide of glass
D. sodium oxide of glass
Answer» B. silicon dioxide of glass
Explanation: 0
1039.

One light year is equal to -

A. 9.46x 10⁻¹7m
B. 9.46x 10¹7m
C. 9.46x 10⁻¹³m
D. 9.46x 10¹³m
Answer» B. 9.46x 10¹7m
Explanation: A light-year is the distance light travels in one year. How far is that? Multiply the number of seconds in one year by the number of miles or kilometers that light travels in one second, and there you have it: one light-year.
1040.

Which gas is used in fire extinguishers?

A. Carbon dioxide
B. Nitrogen oxide
C. Carbon monoxide
D. Sulpher dioxide
Answer» A. Carbon dioxide
Explanation: Sodium bicarbonate, regular or ordinary used on class B and C fires, was the first of the dry chemical agents developed. In the heat of a fire, it releases a cloud of carbon dioxide that smothers the fire.
1041.

Combustion of a candle is a/an -

A. photochemical reaction
B. physical change
C. endothermic reaction
D. exothermic reaction
Answer» D. exothermic reaction
Explanation: In theory, a candle is made of a solid hydrocarbon called paraffin. When the solid burns, the hydrocarbon reacts with oxygen to form carbon dioxide and water. The reaction is exothermic, meaning it releases heat to the atmosphere along with the other products.
1042.

Another name for baking soda is :

A. Sodium bicarbonate
B. Sodium carbonate
C. Sodium sulphate
D. Sodium hydroxide
Answer» A. Sodium bicarbonate
Explanation: Sodium bicarbonate (NaHCO2)is known as baking soda.
1043.

Who invented the modern Periodic table?

A. Faraday
B. Mendeleev
C. Newton
D. Bohr
Answer» B. Mendeleev
Explanation: Dmitri Mendeleev was a Russian chemist who developed the periodic classification of the elements in 1869 A.D.
1044.

Brass is an alloy of -

A. Nickel and Copper
B. Copper and Silver
C. Nickel and Zinc
D. Zinc and Copper
Answer» D. Zinc and Copper
Explanation: Brass is an alloy of copper and zinc, in proportions which can be varied to achieve varying mechanical and electrical properties.
1045.

"Bhopal gas tragedy" 1984 is related to –

A. Aluminium Phosphide
B. Methyl bromide
C. Methyl isocyanate
D. Carbon dioxide
Answer» C. Methyl isocyanate
Explanation: In the Bhopal disaster which took place on 2-3 December, 1984 over 500,000 people were exposed to methyl isocyanate gas and other chemicals. The toxic substance made its way in and around the shantytowns located near the plant.
1046.

The percentage of nitrogen present in ammonium sulphate is –

A. 27%
B. 25%
C. 30.5%
D. 18%
Answer» A. 27%
Explanation: Ammonium sulfate, (NH4)4SO4 contains 21% nitrogen as ammonium cations, and 24% sulfur as sulfate anions. It is an inorganic salt which is most commonly used as a soil fertilizer.
1047.

Surface water is a better source of drinking water because it is poor in -

A. Dust
B. Bacteria
C. Arsenic
D. Algae
Answer» C. Arsenic
Explanation: Surface water is a better source of drinking water because it is poor in arsenic.
1048.

Saturated hydrocarbons are called -

A. Alkynes
B. Alkenes
C. Alkanes
D. All of the above
Answer» C. Alkanes
Explanation: Carbon compounds which contain just carbon and hydrogen are called hydrocarbons. Among these, the saturated hydrocarbons are called alkanes. The unsaturated hydrocarbons which contain one or more double bonds are called alkenes.
1049.

Which one of the following elements is polyatomic?

A. Argon
B. Sodium
C. Sulphur
D. Oxygen
Answer» C. Sulphur
Explanation: The term polyatomic is used for a molecule or an ion which contains either two or more than two atoms.
1050.

Which of the following is not a chemical reaction?

A. Burning of paper
B. Digestion of food
C. Conversion of water into steam
D. Burning of coal
Answer» C. Conversion of water into steam
Explanation: Water boiling is a physical reaction only because during physical reaction there is a change of state but during chemical reaction there is breaking or making of bonds.
1051.

Which type of fire extinguisher is used for petroleum fire?

A. Foam type
B. Soda acid type
C. Powder type
D. None of these
Answer» A. Foam type
Explanation: Foam type fire extinguishers are suitable for fires that involve flammable or combustible liquids, including petrol, grease, and oil. They are applied to fuel fires as either an aspirated (mixed & expanded with air in a branch pipe) or nonaspirated form to form a frothy blanket or seal over the fuel, preventing oxygen reaching it. Powder types are useful for combustible metals.
1052.

The function of skimming tank in sewage treatment is to remove –

A. oil and fatty substances
B. suspended solids
C. gritty substances
D. inorganic substances
Answer» A. oil and fatty substances
Explanation: Oil and grease traps are small size skimming basins provided to remove oil and grease and other small floating materials such as fats, vegetable debris, fruit skins, etc. It is so designed that lighter materials like grease and oil content of wastewater rise to the surface of wastewater and remains on top of liquid until removed.
1053.

Who discovered Oxygen?

A. Carl Scheele
B. Hooke
C. Heisenberg
D. Williams
Answer» A. Carl Scheele
Explanation: Oxygen was discovered for the first time by a Swedish Chemist, Carl Wilhelm Scheele in 1772.He called the gas "fire air".
1054.

Which one among the following is used as a moderator in nuclear reactors?

A. Ozone
B. Heavy hydrogen
C. Hydrogen peroxide
D. Heavy water
Answer» D. Heavy water
Explanation: A pressurized heavy-water reactor (PHWR) is a nuclear reactor, commonly using natural uranium as its fuel, that uses heavy water (deuterium oxide D2O) as its coolant and neutron moderator.
1055.

Which one of the following is used as preservative for foodstuff?

A. Sodium Benzoate
B. Picric acid
C. Glycerine
D. Sodium Chloride
Answer» A. Sodium Benzoate
Explanation: Sodium benzoate is a preservative. It is bacteriostatic and fungistatic under acidic conditions. It is most widely used in acidic foods such as salad dressings (vinegar), carbonated drinks (carbonic acid), jams and fruit juices (citric acid), pickles (vinegar), and condiments. It is also used as a preservative in medicines and cosmetics.
1056.

The element with highest first ionization energy is -

A. hydrogen
B. helium
C. lithium
D. sodium
Answer» B. helium
Explanation: The first ionisation energy is the energy required to remove the most loosely held electron from one mole of gaseous atoms to produce 1 mole of gaseous ions each with a charge of 1+. The first first ionisation energy (in KJ per mole) of Hydrogen: around 1200:Helium: about 2500; Lithium: about 500; and Sodium: about 500.
1057.

The chief source of naphthalene is –

A. Coal-tear
B. Diesel
C. Charcoal
D. Camphor
Answer» A. Coal-tear
Explanation: Coal tar is a brown or black liquid of extremely high viscosity. In the coal gas era, there were many companies in Britain whose business was to distill coal tar to separate the higher-value fractions, such as naphtha, creosote and pitch. Naphthalene is derived from a kind of naphtha (a broad term encompassing any volatile, flammable liquid hydrocarbon mixture, including coal tar).
1058.

KMnO4 can be used as a/an -

A. insecticide
B. fertiliser
C. pesticide
D. disinfectant
Answer» D. disinfectant
Explanation: Potassium permanganate is an inorganic chemical compound with the formula KMnO4. As an oxidant, potassium permanganate can act as an antiseptic. For example, dilute solutions are used to treat canker sores (ulcers), disinfectant for the hands and treatment for mild pompholyx, dermatitis, and fungal infections of the hands or feet. It is used extensively in the water treatment industry.
1059.

Seaweeds are important source of –

A. fluorine
B. chlorine
C. bromine
D. iodine
Answer» D. iodine
Explanation: Seaweed is a source of iodine, necessary for thyroid function and to prevent goitre. However, an excess of iodine is suspected in the heightened cancer risk in Japanese who consume a lot of the plant.
1060.

The resources which can be used continuously, year-after-year are called –

A. Biotic
B. Abiotic
C. Non-renewable
D. Renewable
Answer» D. Renewable
Explanation: A renewable resource is a natural resource with the ability to reproduce through biological or natural processes and replenished with the passage of time. Renewable resources are part of our natural environment and form our eco-system.
1061.

Match sticks are made of -

A. Red phosphorus
B. blue phosphorus
C. led nitrate
D. None
Answer» A. Red phosphorus
Explanation: Red phosphorus is used in matches. Ferrophosphorus, a combination of phosphorus with iron, is used as an ingredient in high-strength low-alloy steel.
1062.

Newlands' table, the elements were placed with the halogens -

A. Mn and As
B. Fe and Se
C. Ce and La
D. Co and Ni
Answer» D. Co and Ni
Explanation: Newlands' Law of Octaves suffered from lot of limitations, In order to fit elements into his table, Newlands ad justed two elements in the same slot, but also put some unlike elements under the same note.
1063.

Iron rusts quickly in –

A. Rain water
B. Sea water
C. Distilled water
D. River water
Answer» B. Sea water
Explanation: Water is the enabler of fast oxidation of iron. So freshwater will also cause rust. However, salt water (sea water) is a very good conductor (lots of dissociated ions) and so there are a number of electrolysis reactions that tremendously accelerate corrosion in salt water. This effect can be reversed by using a metal (like zinc) which causes the current to be re-versed and in effect the zinc corrodes rapidly, protecting the iron.
1064.

Aerated water contains –

A. SO2
B. NO2
C. NO2
D. CO2
Answer» D. CO2
Explanation: Aerated water is, correctly speaking, water to which air is added. So aerated water is any water artificially impregnated with a large amount of has (as carbon dioxide). The term is, however, frequently applied to carbonated water.
1065.

In electro-refining, the pure metal is deposited on –

A. vessel
B. electrolyte
C. cathode
D. anode
Answer» C. cathode
Explanation: In electro-refining, the anodes consist of unrefined impure metal, and as the current passes through the acidic electrolyte the anodes are corroded into the solution so that the electroplating process deposits refined pure metal onto the cathodes. Electrolytic refining is used to extract impurities from crude metals.
1066.

Natural rubber is a polymer of –

A. Vinyl acetate
B. Propene
C. Isoprene
D. Styrene
Answer» C. Isoprene
Explanation: Natural rubber consists of suitable polymers of the organic compound isoprene, with minor impurities of other organic compounds plus water. Isoprene is produced and emitted by many species of trees into the atmosphere (major producers are oaks, poplars, eucalyptus, and some legumes).
1067.

Which among the following is used as a catalyst in the production of high octane fuels?

A. HNO3
B. H2SO4
C. HCl
D. HF
Answer» B. H2SO4
Explanation: Sulfuric acid is used as a catalyst for refining and for producing alkylate, an essential component of highoctane fuel. The hydrocarbon molecules are reformed into more complex molecules with a higher octane rating value.
1068.

Th effect or response produced by two or more chemicals are less than the sum of the effects or response that the chemical would produce individually is known as -

A. Antagonism
B. Independent
C. Additive
D. Synergism
Answer» A. Antagonism
Explanation: Synergy is the interaction of multiple elements in a system to produce an effect different from or greater than the sum of their individual effects. On the other hand, antagonism is the combined action of two or more substances to produce an effect less than the sum of their individual effects.
1069.

Which metal is the heaviest in periodic table among the following?

A. Os
B. Pt
C. Pb
D. W
Answer» A. Os
Explanation: The densest chemical element is Osmium (which is a metal). Osmium has a density of around 22 grams per cubic centimeter, about twice the density of lead.
1070.

The chemical formula of the laughing gas is –

A. NO
B. N2O
C. NO2
D. N2O3
Answer» B. N2O
Explanation: Nitrous oxide, commonly known as laughing gas, is a chemical compound with the formula N2O. It is an oxide of nitrogen.
1071.

Radioactive elements emit –

A. Radiowaves
B. Infrared waves
C. Ultraviolet waves
D. α, β and γ radiations
Answer» D. α, β and γ radiations
Explanation: The phenomenon of spontaneous emission of certain kinds of radiations by some elements is called radioactivity and the elements emitting such radiations are called radioactive elements. The nature of the radiations emitted from a radioactive substance was investigated by Rutherford in 1904 by applying electric and magnetic fields to the radiations. It is observed that on applying the field, the rays emitted from the radioactive substances are separated in to three types, called a, b and g rays.
1072.

Which one out of the following helps in burning?

A. Oxygen
B. Carbon monoxide
C. Nitrogen
D. Carbon dioxide
Answer» A. Oxygen
Explanation: Karl Scheele, the Swedish chemist, was the first to prepare oxygen by heating mercuric oxide in 1772. Joseph Priestley, the English chemist, also prepared oxygen in 1774 by focusing the sun's rays with the help of a lens on mercuric oxide. Its elemental nature was, however, established by the French chemist, Lavoisier.
1073.

Which one of the following is a mixture of carbon monoxide and hydrogen?

A. coal gas
B. producer gas
C. water gas
D. gobar gas
Answer» C. water gas
Explanation: Water gas is a mixture of carbon monoxide and hydrogen produced from synthesis gas. It is a poisonous, colorless gas and burns with an almost colorless flame (light blue).
1074.

Which of the following elements has the lowest melting point?

A. Bromine
B. Zinc
C. Calcium
D. Lead
Answer» A. Bromine
Explanation: Bromine is a chemical element with symbol Br and atomic number 35. Thus, the melting and boiling points of bromine are intermediate between those of chlorine and iodine.
1075.

The chemical substance present in bones and teeth is -

A. Calcium phosphate
B. Calcium chloride
C. Calcium sulphate
D. Calcium borate
Answer» A. Calcium phosphate
Explanation: Seventy percent of bone consists of hydroxyapatite, a calcium phosphate mineral (known as bone mineral). Tooth enamel is composed of almost ninety percent hydroxylapatite.
1076.

The percentage of carbon in cost iron is

A. 0.01 to 0.25
B. 0.5 to 1.5
C. 6 to 3
D. 3 to 5
Answer» D. 3 to 5
Explanation: Cast Iron is a hard, brittle, nonmalleable iron-carbon alloy, cast into shape. It contains 2 to 4.5 percent carbon, 0.5 to 3 percent silicon, and lesser amounts of sulfur, manganese, and phosphorus.
1077.

The compound that has the least value for octane number is –

A. 2-methyl heptane
B. Iso-octane
C. 2,2-dimethyl hexane
D. n-heptane
Answer» D. n-heptane
Explanation: Octane rating or octane number is a standard measure of the performance of a motor or aviation fuel. The higher the octane number, the more compression the fuel can withstand. Isooctane (upper) has an octane ratingof 100 whereas n-heptane has an octane rating of O.
1078.

Which of the following is a correct pair according to increasing atomic number from left to right?

A. Ca, Cl
B. Be, B
C. Na, Ne
D. He, H
Answer» B. Be, B
Explanation: The correct pair is Be and B. Beryllium (Be) has atomic number of 4, while the atomic number of Boron (2) is 5.
1079.

The gas causing acid rain in an industrial area is -

A. Carbon dioxide
B. Carbon monoxide
C. Sulphur dioxide
D. Methane
Answer» C. Sulphur dioxide
Explanation: The main gases responsible for causing acid rain are sulphur dioxide as well as nitrous oxides. The main sources of sulphur dioxide are metal working industries and coal- fired power stations whereas nitrous oxide is from vehicles and fuel combustion.
1080.

Which one of the following has greatest mass?

A. electron
B. proton
C. neutron
D. hydrogen nucleus
Answer» C. neutron
Explanation: 0
1081.

A colloidal system in which a liquid is dispersed in a liquid is called –

A. gel
B. emulsion
C. sol
D. precipitate
Answer» B. emulsion
Explanation: An emulsion is a mixture of two or more liquids that are normally immiscible (nonmixable or unblendable). Emulsions are part of a more general class of two-phase systems of matter called colloids. In an emulsion, one liquid (the dispersed phase) is dispersed in the other (the continuous phase). Examples of emulsions include vinaigrettes, milk, mayonnaise, and some cutting fluids for metal working.
1082.

When a lead storage battery is discharged -

A. SO2 is evolved
B. Lead sulphate is consumed
C. Lead is formed
D. Sulphuric acid is consumed
Answer» D. Sulphuric acid is consumed
Explanation: Lead storage battery was invented by French physicist Gaston Plante in 1859. In the discharged state both the positive and negative plates become lead sulphate and the electrolyte loses much of its dissolved sulphuric acid and becomes primarily water.
1083.

Chemically fats and oils are:

A. Triesters
B. Amines
C. Aldehydes
D. Ketons
Answer» A. Triesters
Explanation: Fats and oils are called triglycerides (or triacylcylgerols) because they are esters composed of three fatty acid units joined to glycerol, a trihydroxy alcohol. Fats and oils are composed of molecules known as triglycerides, which are esters.
1084.

Atomic number of which of the following elements is greater than that of Fluorine?

A. Sodium
B. Beryllium
C. Nitrogen
D. Boron
Answer» A. Sodium
Explanation: Sodium has higher atomic number (11) than Fluorine (9) The atomic number of Beryllium and Nitrogen are 4 and 7 respectively.
1085.

Which of the following is a Synthetic rubber?

A. Leoprene
B. Monoprene
C. Neoprene
D. Isoprene
Answer» C. Neoprene
Explanation: Neoprene Rubber, also known as polychloroprene or PC Rubber, is an extremely versatile synthetic rubber offering oil, petroleum and weathering resistance.
1086.

Washing soda is the common name of-

A. Calcium Carbonate
B. Calcium Bi-Carbonate
C. Sodium Carbonate
D. Sodium Bi-Carbonate
Answer» C. Sodium Carbonate
Explanation: Washing soda, sodium carbonate decahydrate, efflorescent crystals used for washing, especially textiles. It is a compound of sodium (q.v.).
1087.

Which one of the following is known as the 'brown coal'?

A. Anthracite
B. Bituminous
C. Coke
D. Lignite
Answer» D. Lignite
Explanation: Lignite, often referred to as brown coal, is a soft brown fuel with characteristics that put it somewhere between coal and peat. It is considered the lowest rank of coal. It has a carbon content of around 2535%, a high inherent moisture content sometimes as high as 66%, andan ash content ranging from 6% to 19% compared with 6% to 12% for bituminous coal.
1088.

Maximum permissible concentration of copper in drinking water in mg/L, is –

A. 0.01
B. 0.05
C. 1.0
D. 2.0
Answer» C. 1.0
Explanation: The 1959 WHO International Standards for Drinking Water suggested that concentrations of copper greater than 1.5 mg/litre would markedly impair the potability of the water. However, in the first edition of the Guidelines for Drinking Water Quality, published in 1984, a guideline value of 1.0 mg/litre was established for copper, based on its laundry and other staining properties.
1089.

Oxygen has (+) oxidation number only in –

A. OF2
B. Cl2O
C. H2O
D. N2O
Answer» A. OF2
Explanation: In case of F2O, oxygen is not the most electronegative element. The fluorine is more electronegative and has an oxidation state of -1. In this case, the oxygen has an oxidation state of +2.
1090.

Which one of the following elements is used in the manufacture of fertilizers?

A. Fluorine
B. Potassium
C. Lead
D. Aluminium
Answer» B. Potassium
Explanation: Nitrogen, phosphorus and potassium are the three most common bases of fertilizers. Potash can be used to make potassium (K) fertilizers. All commercial potash depositscome originally from marine deposits and are often buried deep in the earth.
1091.

Select the one which is not a mixture –

A. Air
B. Gasoline
C. LPG
D. Distilled water
Answer» D. Distilled water
Explanation: Water (H2O) is the most abundant compound on Earth's surface. Water is a compound because it contains oxygen and hydrogen which are chemically combined in proportion.
1092.

When Hydrogen starts burning in air, it produces?

A. Ammonia
B. Water
C. Methane
D. Carbonic Acid
Answer» B. Water
Explanation: Hydrogen burns in oxygen or air to form water. 2H2 + O2 = 2H2O
1093.

Carbon occurs in nature in the purest form as -

A. Diamond
B. Graphite
C. Carbon black
D. Coal
Answer» A. Diamond
Explanation: There are three forms of pure carbon: Graphite, Coal and Diamond. All three are made up of elemental carbon, caol is the least pure when found in nature. Diamond is the purest form of Carbon.
1094.

In an oxygen molecule, two atoms are united by -

A. one bond
B. two bonds
C. three bonds
D. four bonds
Answer» B. two bonds
Explanation: Two oxygen atoms can both achieve stable structures by sharing two pairs of electrons as in the diagram. Two electrons of each of the atom in the oxygen molecule make the double bond with each other. The double bond is shown conventionally by two lines joining the atoms. Each line represents one pair of shared electrons.
1095.

The inert gas which is substituted for nitrogen in the air used by deep sea divers for breathing is –

A. Neon
B. Krypton
C. Argon
D. Helium
Answer» D. Helium
Explanation: Helium is used by deep sea divers because it reduces the narcosis of nitrogen and it remains below the oxygen toxicity limits. In fact, they use tri mix of Oxygen, helium and a little bit of nitrogen.
1096.

Rectified spirit is :

A. 95% ethyl alcohol
B. 100% ethyl alcohol
C. methylated spirit
D. tincture iodine
Answer» A. 95% ethyl alcohol
Explanation: Rectified spirit, also known as ethyl alcohol of agricultural origin, is highly concentrated ethanol which has been purified by means of repeated distillation, called rectification. It typically contains 95% alcohol by volume.
1097.

Nylon is made up of :

A. Polyamide
B. Polyester
C. Polyethylene
D. Polypropylene
Answer» A. Polyamide
Explanation: Nylon is a generic designation for a family of synthetic polymers knowngenerically as aliphatic polyamides. It is one of the most commonly used polymers.
1098.

Which is a natural colloid?

A. Sodium chloride
B. Urea
C. Cane-sugar
D. Blood
Answer» D. Blood
Explanation: Examples of natural colloids can be found in our body itself: blood consists of colloidal sized red blood corpuscles (RBC) which provide the vital oxygen to all the body tissues.
1099.

Which one of the following does not contain Silver?

A. Ruby Silver
B. Lunar Caustic
C. German Silver
D. Horn Silver
Answer» C. German Silver
Explanation: Nickel silver, also known as German silver, is a copper alloy with nickel and often zinc. The usual formulation is 60% copper, 20% nickel and 20% zinc. Nickel silver is named for its silvery appearance, but it contains no elemental silver unless plated.
1100.

Which of the following auto mobile gases is not considered to be an air pollutant?

A. Carbon dioxide
B. Carbon monoxide
C. Sulfur dioxide
D. Nitrogen dioxide
Answer» A. Carbon dioxide
Explanation: There are mainly six air pollutants: carbon monoxide lead, ground-level ozone, nitrogen dioxide, particulate matter, and sulfur dioxide.
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