1240+ Chemistry Solved MCQs


What is "milk of magnesia" chemically?

A. Magnesium carbonate
B. Sodium bicarbonate
C. Calcium hydroxide
D. Magnesium hydroxide
Answer» D. Magnesium hydroxide
Explanation: agnesium hydroxide is an inorganic compound with the chemical formula Mg(OH)2. As a suspension in water, it is often called milk of magnesia because of its milk-like appearance. The solid mineral form of magnesium hydroxide is known as brucite.

Milk tastes sour when kept in the open for sometime due to the formation of –

A. lactic acid
B. citric acid
C. acetic acid
D. carbonic acid
Answer» A. lactic acid
Explanation: Like many other things, milk contains bacteria, Milk also naturally contains a kind of sugar known as "lactose." The bacteria that live in milk get energy from this special sugar and use it to reproduce to make even more bacteria. When the bacteria use the lactose sugars to reproduce, they change it from "lactose sugar" into "lactic acid," which tastes sour.

Which of the following is a natural dye?

A. Crystal violet
B. Aniline blue
C. Alizarin
D. Phenolphthalein
Answer» C. Alizarin
Explanation: Alizarin or 1,2- dihydroxyanthraquinone (also known as Mordant Red 11 and Turkey Red is an organic compound with formula C14H8O4 that has been used throughout history as a prominent red dye, principally for dyeing textile fabrics. Historically it was derived from the roots of plants of the madder genus. In 1869, it became the first natural pigment to be duplicated synthetically.

The ratio of pure gold in 18 carat gold is

A. 60%
B. 75%
C. 80%
D. 90%
Answer» B. 75%
Explanation: There are various grades of gold purity, determined by the ratio of their alloy composition and rated by a karat system. Typical karat purities range from 10 karats to 24 karats (pure gold), with a wide variation of usage from country to country, 18 karat gold consists of 75% gold and 25% alloy metals. 18 karat gold has been found to be the perfect balance between gold purity and strength. Brilliance offers a variety of exquisite 18 karat gold jewelry.

               is the process in which acids and bases react to form salts and water.

A. Neutralization
B. Electrolysis
C. Distillation
D. Hydrolysis
Answer» A. Neutralization
Explanation: Neutralization is a process when acids and bases react to form salt and water.

The gas usually causing explosions in coal mines is –

A. Hydrogen
B. Carbon monoxide
C. Air
D. Methane
Answer» D. Methane
Explanation: Firedamp is flammable gas found in coal mines. It is the name given to a number of flammable gases, especially methane.

Which is the purest form of iron?

A. Steel
B. Cast iron
C. Pig iron
D. Wrought iron
Answer» D. Wrought iron
Explanation: Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element (by mass) forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust. Wrought iron is the purest form of iron. It contains less than 0.25% carbon.

Which of the following metals form an amalgam with other metals?

A. Lead
B. Tin
C. Zinc
D. Mercury
Answer» D. Mercury
Explanation: An amalgam is a substance formed by the reaction of mercury with another metal. Almost all metals can form amalgams with mercury, notable exception being iron. Silver-mercury amalgams are important in dentistry, and gold-mercury amalgam is used in the extraction of gold from ore. Dentistry has used alloys of mercury with metals such as silver, copper, indium, tin and zinc. Amalgam is an "excellent and versatile restorative material" and is used in dentistry for a number of reasons.

Petroleum is a mixture of –

A. elements
B. hydrocarbons
C. polymers
D. salts
Answer» B. hydrocarbons
Explanation: Petroleum or crude oil is a naturally occurring flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds, that are found in geologic formations beneath the Earth's surface. A fossil fuel, it is formed when large quantities of dead organisms, usually zooplankton and algae, are buried underneath sedimentary rock and undergo intense heat and pressure.

The gas used for filling weather balloons is –

A. helium
B. hydrogen
C. air
D. nitrogen
Answer» A. helium
Explanation: A balloon is an inflatable flexible bag filled with a gas, such as helium, hydrogen, nitrous oxide, oxygen, or air. Modern balloons can be made from materials such as rubber, latex, polychloroprene, or a nylon fabric, while some early balloons were made of dried animal bladders, such as the pig bladder. Some balloons are used for decorative purposes, while others are used for practical purposes such as meteorology, medical treatment, military defense, or transportation.

An emulsion is a colloid of a –

A. gas in a liquid
B. liquid in a liquid
C. liquid in a gas
D. gas in a solid
Answer» B. liquid in a liquid
Explanation: An emulsion is a mixture of two or more liquids that are normally immiscible (nonmixable or unblendable). Emulsions arepart of a more general class of two-phase systems of matter called colloids. Although the terms colloid and emulsion are sometimes used interchangeably, emulsion should be used when both the dispersed and the continuous phase are liquids. 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.

Percentage of carbon in steel ranges from –

A. 0.1 to 1.5
B. 1.5 to 3.0
C. 3.0 to 4.0
D. 4.0 to 6.0
Answer» A. 0.1 to 1.5
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.

Which of the following gases makes bread or cake rise making them soft and spongy?

B. H2
C. CO2
D. O2
Answer» C. CO2
Explanation: Breads rise due to the process of fermentation, a chemical process by which molecules such as glucose are broken down an aerobically.

Candle is a mixture of –

A. Paraffin wax and stearic acid
B. Bees wax and stearic acid
C. Higher fat acids and stearic acid
D. Bees wax and paraffin wax
Answer» A. Paraffin wax and stearic acid
Explanation: The candle can be made of paraffin (a byproduct of petroleum refining), microoystalline wax, stearin (now produced almost exclusively from palm waxes though initially manufactured from animal fats), beeswax (a byproduct of honey collection), gel (a mixture of polymer and mineral oil), some plant waxes (generally palm, carnauba, bayberry, or soybean wax), tallow (rarely used since the introduction of affordable and cheap wax alternatives) or spermaceti (extracted from the head of a Sperm Whale).

German silver, an alloy, does not contain the metal –

A. Nickel
B. Zinc
C. Copper
D. Silver
Answer» D. Silver
Explanation: Nickel silver is a copper alloy with nickel and oft6n. 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. The name "German silver" refers to its development by 19th-century German metalworkers in imitation of the Chinese alloy known as paktong (Cupronickel) All modern, commercially important nickel silvers (such as those standardized under ASTM B 122) contain significant amounts of zinc, and are sometimes considered a subset of brass.

Oxygen which is vital for life is a product of photosynthesis and comes from –

A. carbonates from soil
B. carbon dioxide
C. water
D. oxides of mineral elements
Answer» C. water
Explanation: The unusually high concentration of oxygen has on Earth is the result of the oxygen cycle. This biogeochemical cycle describes the movement of oxygen within and between itsthree main reservoirs on Earth: the atmosphere, the biosphere, and the lithosphere. The main driving factor of the oxygen cycle is photosynthesis, which is responsible for modern Earth's atmosphere. Photosynthesis releases oxygen into the atmosphere, while respiration and decay remove it from the atmosphere.

What is the purpose of adding baking soda to dough?

A. To generate moisture
B. To give a good flavour
C. To give good colour
D. To generate carbon dioxide
Answer» D. To generate carbon dioxide
Explanation: 0

Gobar gas mainly contains –

A. Carbon dioxide
B. Carbon monoxide
C. Hydrogen sulphide
D. Methane
Answer» D. Methane
Explanation: Biogas or Lobar gas is produced by the anaerobic digestion or fermentation of biodegradable materials such as biomass, manure, sewage, municipal waste, green waste, plant material, and crops. It comprises primarily methane (CH4) and carbon dioxide (CO2) and may have small amounts of hydrogen sulphide (H2S), moisture and siloxanes.

The chief constituent of vinegar is –

A. Formic acid
B. Acetic acid
C. Salycylic acid
D. Oxalic acid
Answer» B. 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 mildacid, it had a great variety of industrial, medical, and domestic uses.

Commercial Vaseline is derived from -

A. plant gums
B. coal tar
C. wool wax
D. petroleum
Answer» D. petroleum
Explanation: Vaseline is a brand of petroleum jelly based products owned by Anglo-Dutch company Unilever. While Vaseline can be used as a lubricant, it is also a useful moisture insulator for local skin conditions characterized by tissue dehydration. Vaseline helps protect minor cuts and burns.

Colour imparted to the Bunsen flame by strontium salt is -

A. bluish green
B. apple-green
C. brick red
D. crimson red
Answer» D. crimson red
Explanation: A flame test is performed by introducing a sample into the blue flame of a bunsen burner and noting any change in the colour of the flame. The tests can be used to detect the presence of some metallic elements in salts. With strontium salt, the colour of Bunsen flame ranges from crimson to red.

Name the particle that is most essential to continue the chain reaction during the fission of uranium -

A. Electron
B. Proton
C. Neutron
D. Positron
Answer» C. Neutron
Explanation: Nuclear fission is either a nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into smaller parts (lighter nuclei), often producing free neutrons and photons (in the form of gamma rays), and releasing a very large amount of energy, even bythe energetic standards of radioactive decay. Fission as encountered in the modern world is usually a deliberately produced manmade nuclear reaction induced by a neutron.

Which one amongst the following is not a Green House gas?

A. Nitrogen
B. Carbon dioxide
C. Carbon Monoxide
D. Chloro fluoro carbons
Answer» A. Nitrogen
Explanation: A greenhouse has (sometimes abbreviated GHG) is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. The primary greenhouse gases in the Earth's atmosphere are water vapour, carbon dioxide, methane, nitrous oxide, and ozone.

The element used in the manufacture of safety matches is –

A. Phosphorous
B. Magnesium
C. Silicon
D. Sulphur
Answer» A. Phosphorous
Explanation: One end of a match is coated with a material that can be ignited by frictional heat generated by striking the match against a suitable surface. The coated end of a match, known as the match "head," contains either phosphorus or phosphorus sesquisulfide as the active ingredient and gelatin as a binder.

The main source of Naphthalene is -

A. Charcoal
B. Camphor
C. Coal-tar
D. Diesel
Answer» C. Coal-tar
Explanation: The main source of Naphthalene is coal-tar. Naphthalene is derived from a kindof naphtha which is a broad term encompassing any volatile, namable liquid hydrocarbon mixture, including coaltar.

The material used in solar cells contains

A. Tin
B. Silicon
C. Caesium
D. Thallium
Answer» B. Silicon
Explanation: A solar cell (also called a photovoltaic cell) is an electrical device that converts the energy of light directly into electricity by the photovoltaic effect. Materials presently used for photovoltaic solar cells include mono-crystalline silicon, polycrystalline silicon, amorphous silicon, cadmium telluride, and copper iridium selenide/sulfide.

Quartz is a crystalline form of -

A. Alumina
B. Glass
C. Silica
D. Limestone
Answer» C. Silica
Explanation: Quartz is made up of a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. Tridymite and cristobalite are hightemperature polymorphs of SiO2 that occur in high-silica volcanic rocks. Coesite is a denser polymorph of quartz found in some meteorite impact sites and in metamorphic rocks.

In vulcanisation process, rubber can be hardened by adding -

A. Nitrogen
B. Silicon
C. Sulphur
D. Alcohol
Answer» C. Sulphur
Explanation: In order to give more strength and more elasticity, natural rubber is heated with sulphur or sulphur compounds at 150°Ctemperature. Vulcanized rubber has good tensile strength.

Urea is a -

A. Sodium fertilizer
B. Phosphatic fertilizer
C. Nitrogenous fertilizer
D. Potassium fertilizer
Answer» C. Nitrogenous fertilizer
Explanation: More than 90% of world production of urea is destined for use as a nitrogen-release fertilizer. Urea has the highest nitrogen content of all solid nitrogenous fertilizers in common use.

During inter conversion of energy from one form to other forms, total energy at any time remains–

A. constant
B. zero
C. increasing
D. decreasing
Answer» A. constant
Explanation: During interconversion of energy from one form to other forms, total energy at any time remains constant.

Which of the following is a physical change?

A. oxidation
B. reduction
C. sublimation
D. decomposition
Answer» C. sublimation
Explanation: Sublimation is a type of phase transition, or a change in a state of matter, just like melting, freezing, and evaporation.

Sea weeds are important source of –

A. iron
B. chlorine
C. bromine
D. iodine
Answer» D. iodine
Explanation: Seaweed is a source of iodine, necessaly 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, and even bigger risks in post-mempausal women.

Which gas is used to manufacture vanaspati from vegetable oil is -

A. carbon dioxide
B. nitrogen
C. oxygen
D. hydrogen
Answer» D. hydrogen
Explanation: Hydrogen is used to manufacture vanaspati from vegetable oil.

The pH of a neutral solution is -

A. 0-7
B. 7
C. 7-14
D. None of the above
Answer» B. 7
Explanation: The pH of a neutral solution is 7. Values less than 7 on the pH scale represent an acidic solution. As the pH value increases from 7 to 14, the solution turns more basic.

The nucleus of an atom consists of -

A. electrons and neutrons
B. electrons and protons
C. protons and neutrons
D. All of the above
Answer» C. protons and neutrons
Explanation: The atomic nucleus consists of nucleons—protons and neutrons. Protons and neutrons are made of quarks and held together by the strong force generated by gluon exchange between quarks.

Detergents are –

A. Sodium salts of fatty acids
B. Sodium salts of sulphonic acids
C. Sodium salt of benzoic acid
D. None of the above
Answer» B. Sodium salts of sulphonic acids
Explanation: A detergent is a surfactant or a mixture of surfactants with "cleaning properties in dilute solutiops." These substances are usually alkylbenzenesulfonates, a family of compounds that are similar to soap but are more soluble in hard water, because the polar sulfonate (of detergents) is less likely than the polar carboxyl (of soap) to bind to calcium and other ions found in hard water. In most household contexts, the term detergent by itself refers specifically to laundry detergent or dish detergent, as opposed to hand soap or other types of cleaning agents.

The noble gas used in radiotherapy is

A. neon
B. argon
C. radon
D. xenon
Answer» C. radon
Explanation: An early-20th-century form of quackery was the treatment of maladies in a radiotorium. It was a small, sealed room for patients to be exposed to radon for its "medicinal effects". The carcinogenic nature of radon due to its ionizing radiation became apparent later on. Radon's molecule-damaging radioactivity has been used to kill cancerous cells. It does not, however, increase the health of healthy cells. In fact, the ionizing radiation causes the formation of free radicals, which results in genetic and other cell damage, resulting in increased rates of illness, including cancer.

Ethanol containing 5% water is known as –

A. rectified spirit
B. denatured spirit
C. methylated alcohol
D. power alcohol
Answer» A. rectified spirit
Explanation: A rectified spirit, rectified alcohol, or neutral spirit is highly concentrated ethanol which has been purified by means of

The important ore of aluminium is –

A. bauxite
B. cryolite
C. fluorspar
D. haematite
Answer» A. bauxite
Explanation: Bauxite is an aluminium ore and is the main source of aluminium. This form of rock consists mostly of the minerals gibbsite, boehmite and diaspore , in a mixture with the two iron oxides goethite and hematite, the clay mineral kaolinite, and small amounts of anatase TiO2. Bauxite was named after the village Les Baux in southern France, where it was first recognized as containing aluminium and named by the French geologist Pierre Berthier in 1821.

Which of the following is not present in German-silver?

A. Copper
B. Nickel
C. Silver
D. Zinc
Answer» C. Silver
Explanation: Nickel silver, also known as German silver, Argentan, new silver, nickel brass, albata, alpacca, or electrum, 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. The name "German silver" refers to its development by 19th-century German metalworkers in imitation of the Chinese alloy known as paktong.

The major harmful gas emitted by automobile vehicles which causes air pollution is –

A. Carbon Monoxide
B. Methane
C. Carbon dioxide
D. Ozone gas
Answer» A. Carbon Monoxide
Explanation: Carbon monoxide is the major harmful gas emitted by the automobile vehicles which causes air pollution. Carbon monoxide (CO) - A product of incomplete combustion, carbon monoxide reduces the blood's ability to carry oxygen: overexposure (carbon monoxide poisoning) may be fatal. Carbon Monoxide poisoning is a major killer.

Who discovered the atom bomb?

A. Madam Curie
B. Pierre Curie
C. Otto Hahn
D. Albert Einstein
Answer» C. Otto Hahn
Explanation: Otto Hahn, (8 March, 1879 - 28 July, 1968) was a German chemist and Nobel laureate, a pioneer in the fields of radioactivity and radiochemistry. He is regarded as "the father of nuclear chemistry". On 15 November 1945 the Royal Swedish Academy of Sciences announced that Hahn had been awarded the 1944 Nobel Prize in Chemistry "for his discovery of the fission of heavy atomic nuclei." Otto Hahn received many governmental honours and academic awards from all over the world for his scientific work.

The major component of honey is -

A. glucose
B. sucrose
C. maltose
D. fructose
Answer» D. fructose
Explanation: Honey is a supersaturated sugar solution with approximately 17.1 percent water. Fructose is the predominant sugar at 38.5 percent, followed by glucose at 31 percent.

A body moving in a circular path with a constant speed has a -

A. constant velocity
B. constant acceleration
C. constant kinetic energy
D. constant displacement
Answer» C. constant kinetic energy
Explanation: In circular motion, the magnitude of the velocity of the body is constant but the direction is constantly changing.

is a multibranched polysaccharide of glucose that serves as a form of energy storage in animals and fungi.

A. Cellulose
B. Glycogen
C. Pectin
D. Chitin
Answer» B. Glycogen
Explanation: Glycogen is a multi branched polysaccharide of glucose that serves as a form of emery storage in humans animals, and fungi.

Potassium Permanganate is used for purifying drinking water, because -

A. it dissolves the impurities of water
B. It is a sterilizing agent
C. It is an oxidising agent
D. It is a reducing agent
Answer» C. It is an oxidising agent
Explanation: Potassium permanganate is a point-of-entry treatment method that oxidizes dissolved iron, manganese, and hydrogen sulfide into solid particles that are filtered out of the water.

Diamond is harder than graphite because of –

A. difference in layers of atoms
B. tetrahedral structure of diamond
C. difference of crystalline structures
D. None of these
Answer» A. difference in layers of atoms
Explanation: Diamond is harder than graphite because diamond has a more complex structure. Diamond's structure is like many pentagons connected together, each pentagon sharing a side with another pentagon or each pentagon sharinga point with another pentagon. All the points are linked together in some way. Graphite's structure is very loose, with its bonds forming layers.

Gobar gas contains mainly –

A. methane
B. ethylene
C. propylene
D. acetylene
Answer» A. 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. It also helps in maintaining ecological balance, in rural sanitation and it needs Lower capital cost and almost cost free maintenance.

What is the most commonly used substance in fluorescent tubes?

A. Sodium oxide and argon
B. Sodium vapour and neon
C. Mercury vapour and argon
D. Mercury oxide and neon
Answer» C. Mercury vapour and argon
Explanation: A fluorescent lamp or fluorescent tube is a gas-discharge lamp that uses electricity to excite mercury vapour. it contains mercury vapour and argon. The excited mercury atoms produce short-wave ultraviolet light that then causes a phosphor to fluoresce, producing visible light. A fluorescent lamp converts electrical power into useful light more efficiently than an incandescent lamp.

Which of the following is a super-cooled liquid?

A. Ice-cream
B. Ammonia
C. Glass
D. Wood
Answer» C. Glass
Explanation: Glass is considered to be a super- cooled liquid due to its lack of a first-order phase transition where certain thermodynamic variables such as volume, entropy and enthalpy are discontinuous through the glass transition. range. However, the glass transition may be described as analogous to a second-order phase transition where the intensive thermodynamic variables such as the thermal expansivity and heat capacity are discontinuous.

Soap is prepared by boiling caustic soda with –

A. Alcohol
B. Kerosene oil
C. Glycerine
D. Fats
Answer» D. Fats
Explanation: The most basic kind of soap is made from cuastic soda and animal fat. The two are heated together, and then cooled. The process is called "saponification". In technical terms, saponification involves base (usually caustic soda NaOH) hydrolysis of triglyeerides which are esters of fatty acids, to form the sodium salt, of a carboxylate.

Bronze is an alloy of –

A. Copper and Zinc
B. Tin and Zinc
C. Copper and Tin
D. Iron and Zinc
Answer» C. Copper and Tin
Explanation: Bronze is a metal alloy consisting primarily of copper, usually with tin as the main additive. It is hard and tough, and it was particularly significant in antiquity, so much that the Bronze Age was named after the metal. However, historical pieces were often made interchangeably of bronzes or brasses with different compositions, so modern museum and scholarly descriptions of older objects increasingly use the more inclusive term "copper alloy" instead. Historically the term latten was used for such alloys.

Which of the following elements is non- radioactive?

A. Uranium
B. Thorium
C. Plutonium
D. Zirconium
Answer» D. Zirconium
Explanation: Zirconium is non-radioactive. It is a chemical element with the symbol Zr, atomic number 40 and atomic mass of 91.224. The name of zirconium is taken from the mineral zircon, the most important source of zirconium. It is a lustrous, grey-white, strong transition metal that resembles titanium.

The gas used for artificial fruit ripening of green fruit is –

A. Ethylene
B. Acetylene
C. Ethane
D. Methane
Answer» A. Ethylene
Explanation: Ethylene can promote ripening in tomatoes, bananas, citrus, pineapples, dates, persimmons, pears, apples, melons, mangos, avocados, papayas and jujubes - a clear indication that the action of ethylene is general and widespread amongst a number of fruits. It is clear that ethylene is a ripening hormone - a chemical substance produced by fruits with the specific biological phenomenon of accelerating the normal process of fruit maturation and senescence.

Manganite is an ore/mineral of             .

A. Beryllium
B. Chromium
C. Manganese
D. Copper
Answer» C. Manganese
Explanation: Manganite is an ore mineral of manganese. As a manganese ore, it ranks after pyrolusite and romanechite.

The presence of which of the following salts in water causes corrosion in steam boilers?

A. Sodium Chloride
B. Magnesium Chloride
C. Calcium bicarbonate
D. Potassium bicarbonate
Answer» B. Magnesium Chloride
Explanation: Magnesium chloride is the name for the chemical compound with the formula MgCl2 and its various hydrates MgCl2(H2O)x. These salts are typical ionic halides, being highly soluble in water.

The freezing point of fresh water is -

A. 0°C
B. 4°C
C. 3°C
D. 5 C
Answer» A. 0°C
Explanation: Ocean water freezes just like freshwater, but at lower temperatures. Fresh water freezes at 32 degrees Fahrenheit but seawater freezes at about 28.4 degrees Fahrenheit, because of the salt in it.

             is used for making vinegar.

A. Tartaric acid
B. Malic acid
C. Oxalic acid
D. Acetic acid
Answer» D. Acetic acid
Explanation: Vinegar is a liquid consisting mainly of acetic acid (CH3COOH) and water.

Which of the following elements replaced eka-Aluminium in Mendeleev's Periodic Table?

A. Scandium
B. Gallium
C. Titanium
D. Germanium
Answer» B. Gallium
Explanation: 0

The most reactive among the halogens is -

A. Fluorine
B. Chlorine
C. Bromine
D. Iodine
Answer» A. Fluorine
Explanation: As a general rule, fluorine is the most reactive halogen and astatine is the least reactive. All halogens form Group 1 salts with similar properties.

Which one of the following organic compounds has fruity smell?

A. Alcohol
B. Aldehyde
C. Ester
D. Ether
Answer» C. Ester
Explanation: Esters are common in organic chemistry and biological materials, and often have a characteristic pleasant, fruity odour. This leads to their extensive use in the fragrance and flavor industry. Ester bonds are also found in many polymers. Esterification is the general name for a chemical reaction in which two reactants (typically an alcohol and an acid) form an ester as the reaction product. Esters are widespread in nature and are widely used in industry.

What material is used to make electric heater coil?

A. Copper
B. Iron
C. Silver
D. Nichrome
Answer» D. Nichrome
Explanation: Nichrome is a non-magnetic alloy of nickel, chromium, and often iron, usually used as a resistance wire. Patented in 1905, it is the oldest documented form of resistance heating alloy. A common alloy is 80% nickel and 20% chromium, by mass, but there are many others to accommodate various applications. It is silvery-grey in colour, is corrosion-resistant, and has a high melting point of about 1400 degree C (2552 degree F).

Which one of the following is a major green gas?

A. Carbon dioxide
B. Chloro fluorocarbon
C. Carbon monoxide
D. Freon
Answer» A. Carbon dioxide
Explanation: A greenhouse gas (sometimes abbreviated GHG) is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapour, carbon dioxide, methane, nitrous oxide, and ozone. In the Solar System, the atmospheres of Venus, Mars, and Titan also contain gases that cause greenhouse effects.

Pasteurisation is the process in which milk is heated to –

A. 60°C for 10 minutes
B. 63° C for 20 minutes
C. 63°C for 30 minutes
D. 72°C for 10 minutes
Answer» C. 63°C for 30 minutes
Explanation: Pasteurization for pasteurisation) is a process of heating a food, which is usually a liquid, to a specific temperature for a predefined length of time and then immediately cooling it after it is removed from the heat. This process slows spoilage due to microbial growth in thefood. Unlike sterilization, pasteurization is not intended to kill all micro-organisms in the food. Instead, it aims to reduce the number of viable pathogens so they are unlikely to cause disease (assuming the pasteurized product is stored as indicated and is consumed before its expiration date).

What is the maximum Water Vapour content in the atmosphere?

A. 2 to 3 per cent
B. 3 to 4 per cent
C. 4 to 5 per cent
D. 5 to 6 per cent
Answer» B. 3 to 4 per cent
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. Air is the name given to the atmosphere used in breathing and photosynthesis. Dry air contains roughly (by volume) 78.09% nitrogen, 20.95%

Steel contains –

A. 0.1 - 2% carbon
B. 5 - 10% carbon
C. more than 10% carbon
D. no carbon
Answer» A. 0.1 - 2% carbon
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. Carbon and other elements act as a hardening agent, preventing dislocations in the iron atom crystal lattice from sliding past one another.

The chemicals most commonly used for cloud seeding or artificial rainmaking' is/are

A. Silver Iodide
B. Sodium Chloride
C. Dry ice or frozen carbon dioxide
D. (4) All the above
Answer» A. Silver Iodide
Explanation: Cloud seeding, a form of intentional weather modification, is the attempt to change the amount or type of precipitation that falls from clouds, by dispersing substances into the air that serve as cloud condensation or ice nuclei, which alter the rnicrophysical processes within the cloud. The usual intent is to increase precipitation (rain or snow), but hail and fog suppression are also widely practiced in airports. The most common chemicals used for cloud seeding include silver iodide and dry ice (solid carbon dioxide).

The Refrigerant 'FREON' is –

A. Calcium Tetra Fluoride
B. Difluoro Dichloro Methane
C. Fluorspar and Felspar
D. Hydrofluosilicic Acid
Answer» B. Difluoro Dichloro Methane
Explanation: Dichlorodifluorornethane (R-12), is a colourless gas, and usually sold under the brand name Freon-12, is a chlorofluorocarbon halornethane (CFC), used as a refrigrant and aerosol spray propellant. Complying with the Montreal Protocol, its manufacture was banned in the United States along with many other countries in 1994 clue to concerns about damage to the ozone layer. It is soluble in many organic solvents.

  is the number of shells for elements of the 3rd period.

A. "2"
B. "1"
C. "0"
D. "3"
Answer» C. "0"
Explanation: The third period of the periodic table consists of the elements whose atoms has three shells occupied by electrons in its Ground State (when it is not excited or in a reaction).

Which one among the following polymers is used for making bullet-proof material?

A. Polyvinyl chloride
B. Polystyrene
C. Polyethylene
D. Polyamide
Answer» C. Polyethylene
Explanation: A bullet-proof material is made of polyethylene. It is a higher grade of the plastic found in Tupperware.

The isotope of Uranium capable of sustaining chain reaction is -

A. U-235
B. U-238
C. U-239
D. N.O.T.
Answer» A. U-235
Explanation: Uranium is a chemical element with symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table.

Conversion of chemical energy into electrical energy occurs in -

A. Atomic bombs
B. Dynamo
C. A battery
D. Electric heaters
Answer» C. A battery
Explanation: A battery is a form of chemical energy that can be converted to electrical energy. it is a device consisting of one or more electrochemical cells which performs this action. The first battery (or "voltaic pile") was invented in 1800 by Alessandro Volta.

The fuel that is used in modern submarines is –

A. Nuclear fuel
B. Petrol
C. Coal
D. Diesel
Answer» A. Nuclear fuel
Explanation: Nuclear power is now used in all large submarines, but due to the high cost and large size of nuclear reactors, smaller submarines still use diesel-electric propulsion. The ratio of larger to smaller submarines depends on strategic needs. The US Navy, drench Navy, and the British Royal Navy operate only nuclear submarines.

When lime juice is dropped on baking soda, brisk effervescence takes place because the gas evolved is -

A. Hydrogen
B. Oxygen
C. Carbon dioxide
D. All of them
Answer» C. Carbon dioxide
Explanation: When baking soda and lemon juice are added together, the reaction of the two is an acid-based reaction because it involves an acid (citric acid in the lemon juice) reacting with a base (sodium bicarbonate, more commonly known as baking soda). Carbon dioxide, a gas, is produced by the reaction.

The basic chemical building block of natural rubber obtained from trees is –

A. Isoprene
B. Vinyl Chloride
C. Acetylene
D. Neoprene
Answer» A. Isoprene
Explanation: Isoprene was first isolated by thermal decomposition of natural rubber. About 95% of isoprene production is used to produce cis-1,4- polyisoprene---a synthetic version of natural rubber. Natural rubber consists mainly of poly-cis-isoprene with a molecular weight of 100,000 to 1,000,000.

Hydrogen was discovered by -

A. Cavendish
B. Lavosier
C. Rutherford
D. Scheele
Answer» A. Cavendish
Explanation: In 1766, Henry Cavendish was the first to recognize hydrogen gas as a discrete substance, by naming the gas from a metal-acid reaction "flammable air".

Glass is a –

A. pure solid
B. supercooled liquid
C. gel
D. polymer
Answer» B. supercooled liquid
Explanation: Glass is an amorphous (non- crystalline) solid material. Glasses are typically brittle and optically transparent. The standard definition of a glass (or vitreous solid) is a solid formed by rapid melt quenching. However, the term glass is often used to describe any amorphous solid that exhibits a glass transition temperature Tg.

Uranium eventually decays into a stable isotope of —

A. Radium
B. Thorium
C. Lead
D. Polonium
Answer» C. Lead
Explanation: Natural uranium consists of three major isotopes: U238 (99.28% natural abundance), U235 (0.71%), and U234 (0.0054%). All three are radioactive, emitting alpha particles, with the exception that all three of these isotopes have small probabilities of undergoing spontaneous fission, rather than alpha emission. U23° is usually an alpha emitter (occasionally, it undergoes spontaneous fission), decaying through the "Uranium Series" ofnuclear decay, which has 18 members, all of which eventually decay into Pb206, by a variety of different decay paths.

The substance that is added to make natural rubber strong and more bouncy is –

A. Polythene
B. Sponge
C. Sulphur
D. Chlorine
Answer» C. Sulphur
Explanation: Vulcanization 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". These additives modify the polymer by forming crosslinks (bridges) between individual polymer chains. Vulcanized materials are less sticky and have superior mechanical properties.

White phosphorus is always kept under

A. benzene
B. kerosene
C. ether
D. water
Answer» D. water
Explanation: White phosphorus is a material made from a common allotrope of the chemical element phosphorus that is used in smoke, tracer, illumination and incendiary munitions. Other common names include WP, and the slang term "Willie Pete," which is dated from its use in Vietnam, and is still sometimes used in military jargon. As an incendiary weapon, white phosphorus burns fiercely and can set cloth, fuel, ammunition and other combustibles on fire, and cause serious burns or death and that is why it is kept in water.

The amount of Chlorine available in water after disinfection is called as –

A. free chlorine
B. residual chlorine
C. free available chlorine
D. combined available chlorine
Answer» B. residual chlorine
Explanation: The word "residual" means "remainder" or "that which is left", and as the name suggests the chlorine residual is measure of the amount of chlorine remaining in the water after disinfection. The chlorine residual is usually tested in finished water which is ready to be released into the distribution system, although operators must also ensure that there is adequate residual at the extreme ends of the distribution system. Tests for chlorine residual are probably the most frequently performed tests at water treatment plants.

What are the major pollutants of cigarette smoke?

A. Carbon monoxide and dioxin
B. Carbon monoxide and nicotine
C. Carbon monoxide and benzene
D. Dioxin and benzene
Answer» B. Carbon monoxide and nicotine
Explanation: Particulate matter consists of millions of tiny particles of diverse chemical composition. Particulate matter from tobacco smoke includes many particles in the size range that reflects light, which explains why tobacco smoke is easily seen by the eye. In contrast to smoke particles, gases emitted by the cigarette such as benzene and carbon monoxide (CO) are invisible to the eye. Particles smaller than 2.5 micrometers (PM2.5) are major components of cigarette smoke and can enter deep into the lung where they can cause serious health problems.

The chemical name of 'Common salt' is

A. Sodium chloride
B. Sodium nitrate
C. Ammonium chloride
D. Calcium chloride
Answer» A. 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 extracellularfluid of many multicellular organisms. As the major ingredient in edible salt, it is commonly used as a condiment and food preservative. In solid sodium chloride, each ion is surrounded by six ions of, the opposite charge as expected on electrostatic grounds.

By-product obtained by soap industry is –

A. Caustic soda
B. Glycerol
C. Naphthalene
D. Caustic potash
Answer» B. Glycerol
Explanation: Glycerol forms the backbone of triglyeerides, and is chiefly produced by saponification of fats as a byproduct of soap- making. It is also a byproduct of the production of biodiesel via transesterification. This form of crude glycerin is often dark in appearance with a thick, syrup-like consistency.

Polythene is polymer of –

A. Ethylene
B. Propylene
C. Acetylene
D. Aniline
Answer» A. Ethylene
Explanation: The ingredient or monomer is ethylene (IUPAC name ethene). It has the formula C2H4, consisting of a pair of CH2 groups connected by a double bond. Because the catalysts are highly reactive, the ethylene must be of high purity. Typical specifications are <5 ppm for water, oxygen, as well as other alkenes. Acceptable contaminants include N2, ethane (common precursor to ethylene), and methane. Ethylene is usually produced from petrochemical sources, but also is generated by dehydration of ethanol.

Who suggested that the most of the mass of atom is located in nucleus?

A. Bohr
B. Thomson
C. Rutherford
D. Avogadro
Answer» C. Rutherford
Explanation: The atom, as described by Ernest Rutherford, has a tiny, massive core called the nucleus. The nucleus has a positive charge.

Electromagnet is constructed with which of the following?

A. Steel
B. Soft Iron
C. Aluminium
D. Nickel
Answer» B. Soft Iron
Explanation: An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. The magnetic field disappears when the current is turned off. It is made of soft iron since it has the property of losing its magnetism very quickly.

Which one of the following is a cation?

A. Carbonate
B. Nitrite
C. Ammonium
D. Hydroxide
Answer» C. Ammonium
Explanation: The ammonium cation is a positively charged polyatomic cation with the chemical formula NH4+.

Ginger is an example of -

A. Modified Node
B. Modified Root
C. Modified Stem
D. Tap Root
Answer» C. Modified Stem
Explanation: Modified stems that grow above ground: Stolons or runners-are horizontally oriented stems that grow along the soil surface.

The ore which is found in abundance in India is -

A. monazite
B. bauxite
C. magnetite
D. fluorspar
Answer» A. monazite
Explanation: The ore monazite is found in abundance in India.

Baryllium Sulphate is less soluble in water due to –

A. High inflammable energy
B. Low Energy of dissociation
C. Low inflammable energy
D. Lonic band
Answer» A. High inflammable energy
Explanation: Beryllium sulfate (BeSO4) is a white crystalline e solid. It was first isolated in 1815 by Jons Jakob Berzelelu Beryllium sulfate may be prepared by treatingasne aqueous solution of any beryllium salt with sulfuric acid, followed by evaporation of the solution and crystallization. The hydrated product may be converted to anhydrous salt by heating at 400°C. Beryllium Sulphate is less soluble in water due to High inflammable energy.

Which of the following is a not a green house gas?

A. Carbon Dioxide
B. Water Vapour
C. Carbon Monoxide
D. Nitrous Oxide
Answer» C. Carbon Monoxide
Explanation: The primary greenhouse gases in Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide and ozone.

Heat resistant variety of glass is –

A. Pyrex glass
B. Hard glass
C. Flint glass
D. None of these
Answer» C. Flint glass
Explanation: Flint glass is optical glass that has relatively high refractive index and low Abbe number (high dispersion). Flint glasses are arbitrarily defined as having an Abbe number of 50 to 55 or less. The currently known flint glasses have refractive indices ranging between 1.45 and 2.00. A concave lens of flint glass is commonly combined with a convex lens of crown glass to produce an achromatic doublet lens because of their compensating optical properties, which reduces chromatic aberration (colour defects).

Among the following iron ores, the highest percentage of iron content is found in—

A. Haemetite
B. Magnetite
C. Limnonite
D. None of these
Answer» A. Haemetite
Explanation: Hematite, also spelled haematite, heavy and relatively hard oxide mineral, ferric oxide (Fe2SO3), that constitutes the mostimportant iron ore because of its high iron content (70 percent) and its abundance. Its name is derived from the Greek word for "blood," in allusion to its red colour. Many of the various forms of hematite have separate names. The steel-gray crystals and coarse-grained varieties have a brilliant metallic lustre and are known as specular iron ore; thin scaly types are called micaceous hematite.

For determination of the age of which among the following is carbon dating method used?

A. Fossils
B. Rocks
C. Trees
D. 1 & 2 above
Answer» D. 1 & 2 above
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. Raw, i.e., uncelebrated, radiocarbon ages are usually reported in radiocarbon years "Before Present" (BP), with "present" defined as CE 1950. Such raw ages can be calibrated to give calendar dates. One of the most frequent uses of radiocarbon dating is to estimate the age of organic remains from archaeological sites.

The natural source of hydro-carbon is –

A. Crude oil
B. Biomass
C. Coal
D. Carbohydrates
Answer» A. Crude oil
Explanation: In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls. Aromatic hydrocarbons (arenes), alkanes, alkenes, cycloalkanes and alkyne-based compounds are different types of hydrocarbons. The majority of hydrocarbons found naturally occur in crude oil, where decomposed organicmatter provides an abundance of carbon and hydrogen which, when bonded, can catenate to form seemingly limitless chains.

Which of the following is chiefly present in LPG (Liquefied Petroleum Gas)?

A. Methane
B. Ethane
C. Propane
D. Butane
Answer» D. Butane
Explanation: Liquid petroleum gas is a flammable mixture of hydrocarbon gases used as a fuel in heating appliances and vehicles. It is increasingly used as an aerosol propellant and a refrigerant, replacing chlorofluorocarbons in an effort to reduce damage to the ozone layer. it has primarily butane (C4H10).

Which one of the following metals is used to galvanise iron?

A. Copper
B. Lead
C. Zinc
D. Mercury
Answer» C. Zinc
Explanation: Galvanization) is the process of applying a protective zinc coating to steel or iron, in order to prevent rusting. The term is derived from the name of Italian scientist Luigi Galvani. Although galvanization can be done with electrochemical and electro-deposition processes, the most common method in current use is hot-dip galvanization, in which steel parts are submerged in a bath of molten zinc.

Which of the following is not a precious/semi-Precious stone?

A. Sapphire
B. Ruby
C. Pearl
D. Emerald
Answer» C. Pearl
Explanation: A pearl is a hard object produced within the soft tissue (specifically the mantle) of a living shelled mollusk. Just like the shell of aclam, a pearl is made up of calcium carbonate in minute crystalline form, which has been deposited in concentric layers. The ideal pearl is perfectly round and smooth, but many other shapes of pearls (baroque pearls) occur. The finest quality natural pearls have been highly valued as gemstones and objects of beauty for many centuries, and because of this, the word pearl has become a metaphor for something very rare, fine, admirable, and valuable.

What is the name of that system, which uses radioactivity to decide the period of materials of-prehistoric period?

A. Radium dating
B. Uranium dating
C. Carbon dating
D. Deuterium dating
Answer» C. Carbon 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.
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