1240+ Chemistry Solved MCQs

701.

Isotopes differ in -

A. No. of electrons
B. No. of protons
C. No. of neutrons
D. Chemical reactivity
Answer» C. No. of neutrons
Explanation: Isotopes have the same atomic number because they are the same element but have a different atomic mass because they contain a different number of neutrons.
702.

Modern periodic law had been given by

A. Moseley
B. Mendeleev
C. Lother-Mayer
D. Lavoisier
Answer» A. Moseley
Explanation: In 1913, H.G.J Moseley in England proved that the more fundamental properties of an element are its atomic number. Therefore he suggested that the basis of classification of elements should be atomic number.
703.

Iron filings can be separated from a heterogenous mixture using the technique of

A. Sublimation
B. Magnetization
C. Sedimentation
D. Evaporation
Answer» B. Magnetization
Explanation: The method of separation using magnets is used when one of the components is magnetic. So the heterogeneous mixture of iron filings and some other material (such as sulphur powder) can be separated by using magnets. Similarly, a mixture of sand and iron filings can be separated by magnet.
704.

The most abundant element by number in the living system is :

A. Nitrogen
B. Hydrogen
C. Oxygen
D. Carbon
Answer» B. Hydrogen
Explanation: In sequential order, Hydrogen. Oxygen, Carbon and Nitrogen are the most abundant elements by number in the living system. Hydrogen constitutes 49.8% of living systems, while Oxygen constitutes 24.9%; Carbon and Nitrogen account for 24,9% and 0.27% respectively. It is not surprising, therefore, that the living cell is between 60% and 90% water.
705.

Who discovered Potassium?

A. Humphry Davy
B. Alan Turing
C. Bill Gates
D. Tim Berners-Lee
Answer» A. Humphry Davy
Explanation: Potassium metal was first isolated in 1807 in England by Sir Humphry Davy, who derived it from caustic potash (KOH, potassium hydroxide) by electrolysis of molten KOH with the newly discovered voltaic pile.
706.

Air is -

A. Compound
B. Element
C. Mixture
D. Solution
Answer» C. Mixture
Explanation: Pure air is a mixture of several gases that are invisible and colorless. It consists of about 78% nitrogen, 21% oxygen, and less than 1% of argon, carbon dioxide and other gases, as well as varying amounts of water vapour.
707.

What is the formula of potassium ion in the noble gas state?

A. K⁺
B. K²⁺
C. K²⁻
D. K⁻
Answer» A. K⁺
Explanation: 0
708.

The element absorbed both in cation and anion form is –

A. Sulphur
B. Nitrogen
C. Calcium
D. Phosphorus
Answer» B. Nitrogen
Explanation: Nitrogen, required in large quantities for healthy plant growth, is supplied either as a cation (ammonium) or an anion (nitrate). The ratio of these two forms of nitrogen in the nutrient solution can have large effects on both the rate and direction of pH changes with time.
709.

Browning of paper in old books is caused by –

A. frequent use
B. lack of aeration
C. collection of dust
D. oxidation of cellulose
Answer» D. oxidation of cellulose
Explanation: Foxing is a term describing the age-related spots and browning seen on vintage paper documents such as books, postage stamps, certificates, and so forth. It results from localized accelerated oxidation of cellulose or the effect on certain papers of the oxidation of iron, copper, etc.
710.

Which of the following is the hardest metal?

A. Gold
B. Iron
C. Platinum
D. Tungstain
Answer» D. Tungstain
Explanation: Tungsten has the highest tensile strength of any natural metal, with an ultimate strength of 1510 megapascals.
711.

Nuclear sizes are expressed in a unit named -

A. Fermi
B. Angstrom
C. Newton
D. Tesla
Answer» A. Fermi
Explanation: The fermi (1 fm = 10⁻¹7 m) is of the order of magnitude of the size of nucleons and nuclei, so it is more appropriate to describe sizes for nuclear phenomena.
712.

Which one of the following is responsible for the stimulating effect of tea?

A. Tannin
B. Steroid
C. Alkaloid
D. Flavonoid
Answer» C. Alkaloid
Explanation: The stimulating effect of a tea is mainly due to what is called alkaloid caffeine which is then linked with tannin found in a tea leaf.
713.

The contact process is involved in the manufacture of -

A. Nitric acid
B. Sulphuric acid
C. Ammonia
D. Caustic soda
Answer» B. Sulphuric acid
Explanation: It is also a central substance in the chemical industry. It is widely produced by contact process. Now days, sulphuric acid is prepared by contact process all over the world. Preparation of sulphuric acid by contact process is based upon the catalytic oxidation of sulfur dioxide (SO2) to sulfur trioxide (SO3).
714.

Which of the following is the purest form of Carbon?

A. Charcoal
B. Granite
C. Diamond
D. Graphite
Answer» C. Diamond
Explanation: Because the carbon atoms in diamond are more tightly bound than in graphite (as diamond is the hardest material known), it is more difficult for impurities to get into the diamond lattice and as a result diamonds are often more pure than graphite.
715.

Brass is made of –

A. copper and tin
B. tin and lead
C. copper and zinc
D. copper, tin and zinc
Answer» C. copper and zinc
Explanation: Brass is an alloy of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties. By Comparison, bronze is principally an alloy of copper and tin.
716.

The wine is prepared by the process of -

A. fermentation
B. catalysation
C. conjugation
D. displacement
Answer» A. fermentation
Explanation: Like lactic acid fermentation, alcoholic fermentation generates NAD+ so that glycolysis can continue to produce ATP. However, alcoholic fermentation in yeast produces ethyl alcohol instead of lactic acid as a waste product.
717.

Compounds with identical molecular formula but different structures are called -

A. Tetravalent compounds
B. Structural isomers
C. Covalent compounds
D. None of the above
Answer» B. Structural isomers
Explanation: Structures with identical molecular formula but different structures are called structural isomers. Eg: Butane.
718.

PVC is formed by polymerization of -

A. Styrene
B. Acetylene
C. Propene
D. Vinyl Chloride
Answer» D. Vinyl Chloride
Explanation: Polyvinyl chloride is produced by polymerization of the vinyl chloride monomer (VCM). About 80% of production involves suspension polymerization.
719.

The unit to measure the flow of water is -

A. Micro Mho
B. Ohm meter
C. Milli curie
D. Cusecs
Answer» D. Cusecs
Explanation: The unit to measure the flow of water is cusecs. Cusecs is short form of Cubic feet per second.
720.

Which of the following metals occurs in free state?

A. Copper
B. Iron
C. Zinc
D. Lead
Answer» D. Lead
Explanation: A native metal is any metal that is found in its metallic form, either pure or as an alloy, in nature. Metals that can be found as native deposits singly and/ or in alloys include aluminium, antimony, arsenic, bismuth, cadmium, chromium, cobalt, indium, iron,nickel, selenium, tantalum, tellurium, tin, titanium, and zinc, as well as two groups of metals: the gold group, and the platinum group. The gold group consists of gold, copper, lead, aluminium, mercury, and silver
721.

Copper is refined by -

A. roasting
B. oxidation
C. electrolysis
D. zone refining
Answer» A. roasting
Explanation: Copper is refined by the method of roasting. In the roaster, the copper concentrate is partially oxidised to produce "calcine" and sulfur dioxide gas. In roasting, the ore or ore concentrate is treated with very hot air. This process is generally applied to sulphide minerals.
722.

What is the common name of CaOCI2?

A. Baking Powder
B. Baking Soda
C. Bleaching Powder
D. Washing Soda
Answer» C. Bleaching Powder
Explanation: Calcium hypochlorite, an inorganic compound with formula Ca(CIO)2, is commonly known as bleaching powder. It is not highly soluble in water and is more preferably used in soft to medium hard water.
723.

Rutherford’s scattering experiment proved the presence of -

A. atoms in all matter
B. electrons in atoms
C. neutrons in atoms
D. nucleusin atoms
Answer» D. nucleusin atoms
Explanation: Ernest Rutherford and his fellows Geiger and Marsden proved between 1911 and 1913 the existence of the atomic nucleus. This scattering experirnent led to the development of the Rutherford model (planetary model) of the atom, and eventually to the Bohr model.
724.

When a metal is heated in a flame, the electrons absorb energy and jump to higher energy state. On coming back to the lower energy state, they emit light, which we can observe in -

A. Raman spectra
B. Absorption spectra
C. Emission spectra
D. Fluorescence
Answer» C. Emission spectra
Explanation: When a metal atom is strongly heated, its electrons absorb the heat energy and jump to a higher energy level. When the electron returns to its original position it gives off-the energy it absorbed in the form of light. The result of all these jumps is to produce what is called an emission spectrum. An emission spectrum is a set of coloured lines that correspond to the energy the electron has released at each stage °fits fall back to its original state.
725.

Haemoglobin has the highest affinity with which of the following?

A. SO
B. CO₂
C. CO
D. NO₂
Answer» C. CO
Explanation: 0
726.

Which of the following gases is produced due to incomplete combustion of fuel?

A. Carbon Dioxide
B. Carbon Monoxide
C. Methane
D. Ethane
Answer» B. Carbon Monoxide
Explanation: Carbon monoxide (CO) is an odorless, colorless gas formed by the incomplete com bustion of fuels. It is produced from the partial oxidation of carbon-containing com pounds; it forms when there is not enough oxygen to produce carbon dioxide.
727.

Acid used in an automobile battery?

A. Sulphuric acid
B. Hydrochloric acid
C. Nitric acid
D. Citric acid
Answer» A. Sulphuric acid
Explanation: Each cell of an automotive battery consists of alternate plates of lead (cathode) and (anode) immersed in an electrolyte of sulfuric acid solution.
728.

Which of the following is used as lubricant?

A. Graphite
B. Silica
C. Diamond
D. Iron Oxide
Answer» A. Graphite
Explanation: Graphite is used as a lubricant due to its slippery nature. Due to its loosely intact carbon atoms or free electrons, they can move around easily from one place to another, making graphite a good conductor of electricity.
729.

Aquaregia is a mixture of the following in the ratio 1 : 3 by volume–

A. cone. HNO3 and cone. HCL
B. conc. HNO3 and conc. H2SO4
C. dil. HCl and dil. HNO3
D. cone. HCl and cone. HNO3
Answer» C. dil. HCl and dil. HNO3
Explanation: Aqua regia or nitro-hydrochloric acid is a highly corrosive mixture of acids which is formed by freshly mixing concentrated Nitric acid (HNO3) and Hydrochloric acid (HCl), optimally in a volume ratio of 1:3. It is used in dissolving gold.
730.

In deep-sea diving, divers use a mixture of gases consisting of oxygen and –

A. hydrogen
B. nitrogen
C. argon
D. helium
Answer» B. nitrogen
Explanation: Air is not the "ideal" breathing mixture for diving as with a concentration of approximately 79 percent nitrogen, compressed air poses two potential problems for all divers: susceptibility to nitrogen narcosis and at deeper depths; and decompression sickness. So divers use Nitrox, a gaseous mixture of nitrogen and oxygen. It is also known as 'Enriched Air.'
731.

Nucleons are regarded as composites sub-particles known as –

A. Mesons
B. Quarks
C. Leptons
D. Photons
Answer» B. Quarks
Explanation: 0
732.

Which of the following is not a greenhouse gas?

A. Water vapour
B. O2
C. O3
D. CO2
Answer» B. O2
Explanation: Greenhouse gases are those that can absorb and emit infrared radiation, but not radiation in or near the visible spectrum. The most abundant greenhouse gases in Earth's atmosphere are: Water vapor (H2O), Carbon dioxide (CO2), Methane (CH4), Nitrous oxide (N2O), Ozone (O3) and CFCs.
733.

If Metal A displaces Metal B from its solution, then Metal A               .

A. is more reactive than B
B. is less reactive than B
C. is heavier than B
D. has the same reactivity as B
Answer» A. is more reactive than B
Explanation: 0
734.

Who discovered electrons?

A. Rutherford
B. Niels Bohr
C. JJ Thomson
D. Newton
Answer» C. JJ Thomson
Explanation: JJ Thomson, while performing cathode ray experiment found that the cathode ray is made up of very small negatively charged particles to which he termed as electrons.
735.

Which is also called Stranger Gas?

A. Xenon
B. Neon
C. Argon
D. Nitrous oxide
Answer» A. Xenon
Explanation: Xenon is also called Stranger Gas. The element's name came from the Greek word xenos, which means 'stranger'. Xenon belongs to the group of the noble gases.
736.

Silicon is an example of -

A. A metal
B. A non- metal
C. A metalloid
D. Both (2) and (3)
Answer» C. A metalloid
Explanation: Metals like Na and Mg are towards the left-hand side of the Periodic Table while the non-metals like sulphur and chlorine are found on the right-hand side.
737.

The “King of Metals” is :

A. Gold
B. Silver
C. Iron
D. Aluminium
Answer» A. Gold
Explanation: Gold, which is not only the most valuable of metals, but also is without its peer in freedom from alloy, is known as the king of metals. Luxurious, classy and beautiful, gold is the most classic and coveted jewelry metal of all. It is also the oldest precious met-al known to man.
738.

The strongest oxidizing agent among the following is:

A. Chlorine
B. Iodine
C. Fluorine
D. Oxygen
Answer» C. Fluorine
Explanation: An oxidizing agent is a chemical species that removes an electron from another species. Fluorine, having the largest positive value of electrode potential, is the strongest oxidizing agent. As a matter of fact, all halogens have a tendency to take up electrons and thus act as strong oxidizing agents.
739.

A mixture of carbon monoxide and hydrogen is called -

A. Producer gas
B. Water gas
C. Natural gas
D. None
Answer» B. Water gas
Explanation: Water gas is a synthesis gas, containing carbon monoxide and hydrogen. It is a useful product but requires careful handling due to its flammability and the risk of carbon monoxide poisoning.
740.

In Nuclear reactors graphite is used as

A. Lubricant
B. Fuel
C. Linear of the reactor
D. Modulator
Answer» D. Modulator
Explanation: Nuclear reactors are used at nuclear power plants for electricity generation. These are generally graphite moderated and CO2 cooled.
741.

Activated Charcoal is used to remove colouring matter from pure substances by –

A. Bleaching
B. Oxidation
C. Adsorption
D. Reduction
Answer» C. Adsorption
Explanation: Heating wood to a very high temperature in the absence of air makes charcoal. When it is heated to an even higher temperature, about 930°C, impurities are driven from its surface and it becomes activated charcoal, sometimes called decolorizing charcoal. This activated charcoal can remove impurities in either the gaseous or liquid state from many solutions. It does so by the process of adsorption, or by attracting these molecules to the surface.
742.

Chernobyl disaster is the result of pollution by –

A. Oil spill
B. Acid rain
C. Carbon dioxide
D. Radioactive waste
Answer» D. Radioactive waste
Explanation: The Chernobyl disaster was a catastrophic nuclear accident that occurred on 26 April 1986 at the Chernobyl Nuclear Power Plant in the city of Pripyat, then located in the Ukrainian USSR. An explosion and fire released large quantities of radioactive particles into the atmosphere, which spread over much of the western USSR and Europe.
743.

Which one of the following elements exists in liquid state at room temperature?

A. Mercury
B. Lead
C. Sodium
D. Calcium
Answer» A. Mercury
Explanation: Mercury is a dense, silvery d- block element. It is the only metal that is liquid at standard conditions for temperature and pressure.
744.

Bone deformities occur due to excessive intake of:

A. Phosphorus
B. Potassium
C. Fatty acid
D. Fluorine
Answer» D. Fluorine
Explanation: Bone deformities occur due to excessive intake of Fluorine.
745.

The name of the scientist who discovered neutron is -

A. Fermi
B. Rutherford
C. Chadwick
D. Bohr
Answer» C. Chadwick
Explanation: Sir James Chadwick, CH, FRS (20 October 1891 – 24 July 1974) was a British physicist who was awarded the 1935 Nobel Prize in Physics for his discovery of the neutron in 1932.
746.

Of the following commonly used materials, the one that is not an alloy is -

A. Steel
B. Brass
C. Bronze
D. Copper
Answer» D. Copper
Explanation: Copper is not an alloy; it is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. It is used as a constituent of various metal alloys, such as sterling silver used in jewellery, cupronickel used to make marine hardware and coins, and constant an used in strain gauges and thermo- couples for temperature measurement.
747.

Bronze is an alloy of –

A. Copper & tin
B. Copper & zinc
C. Copper & iron
D. Iron & nickel
Answer» A. Copper & tin
Explanation: Bronze is an alloy consisting primarily of copper, commonly with about 12% tin and often with the addition of other metals (such as aluminium, manganese, nickel or zinc) and sometimes non-metals or metalloids such as arsenic, phosphorus or silicon. These additions produce a range of alloys that may be harder than copper alone, or have other useful properties.
748.

Which acid is used in Lead storage batteiy?

A. Sulphuric acid
B. Nitric acid
C. Hydrochlotic acid
D. Acetic acid
Answer» A. Sulphuric acid
Explanation: Lead acid battery is a storage battery or secondary battery in which electrical energy can be stored as chemical energy and this chemical energy is then converted to electrical energy as when required. Leadacid batteries are composed of a Lead-dioxide cathode, a sponge metallic Lead anode and a Sulphuric acid solution electrolyte.
749.

Ethanoic acid is commonly called -

A. Acetic acid
B. Sulphuric acid
C. Sodium Ethoxide
D. Ethyne
Answer» A. Acetic acid
Explanation: Ethanoic acid is commonly called acetic acid and belongs to a group of acids called carboxylic acids. 58% solution of acetic acid in water is called vinegar and is used widely as a preservative in pickles.
750.

The bubbles in Chanmpagne and Soda are -

A. Nitrogen
B. Oxygen
C. Carbon dioxide
D. Hydrogen
Answer» D. Hydrogen
Explanation: 0
751.

Which one is not metal?

A. sulphar
B. sugar
C. nitrogen
D. all
Answer» D. all
Explanation: A metal is a material (an element, compound, or alloy) that is typically hard, opaque, and shiny and has good electrical and thermal conductivity.
752.

What nucleus of atom contains?

A. protons
B. electrons
C. electrons and protons
D. protons and neutrons
Answer» D. protons and neutrons
Explanation: The nucleus, that dense central core of the atom, contains both protons and neutrons. Electrons are outside the nucleus in energy levels.
753.

Which of the following caused radioactive pollution along the coast of Kerala?

A. Plutonium
B. Zinc
C. Thorium
D. Radium
Answer» C. Thorium
Explanation: Thorium-rich monazite sand deposits on the Kerala coast have been responsible for natural radioactive contamination. It has been pronounced on the south-west coastal line of the state. The region has been found to have elevated levels of background radioactivity due to high abundance of thorium.
754.

For extinguishing fire, we use –

A. Hydrogen
B. Carbon Monoxide
C. Carbon Dioxide
D. Marsh has
Answer» C. Carbon Dioxide
Explanation: Fire extinguishers use carbon dioxide to displace the oxygen necessary for a fire to burn, extinguishing the blaze. Fires need oxygen, fuel, and heat to ignite, and removing any one of those three components can put out a fire. It is useful for electrical fires and some flammable liquid fires, but may make some gasoline or paper fires worse by dispersing burning material.
755.

Which of the following metal has the lowest melting point?

A. Lead
B. Lithium
C. Potassium
D. Sodium
Answer» C. Potassium
Explanation: Here, Potassium has the lowest melting point in the given options i.e. 63.5° C. Helium has the lowest melting point of -272.2° C.
756.

The main component of liquid bleach is:

A. Sodium chloride
B. Sodium hypochlorite
C. Hydrochloric acid
D. Sodium hypochlorate
Answer» B. Sodium hypochlorite
Explanation: Sodium hypochlorite bleaches are also called chlorine or liquid household bleach. They are the more powerful laundry bleaches; they are used to whiten and disinfect laundry, is typically either 5.25 percent (regular strength) or 6 percent sodium hypochlorite (ultra strength).
757.

The chemical used as a fixer in photography is -

A. sodium thiosulphate
B. sodium sulphate
C. borax
D. ammonium sulphate
Answer» A. sodium thiosulphate
Explanation: Fixation is commonly achieved by treating the film or paper with a solution of thiosulfate salt. Popular salts are sodium thiosulfate — commonly called hypo — and ammonium thiosulfate — commonly used in modern rapid fixer formulae.
758.

Which of the following is the most abundant metal on Earth's crust?

A. Magnesium
B. Iron
C. Copper
D. Aluminium
Answer» D. Aluminium
Explanation: Aluminum is the most abundant metal in the Earth's crust, and the third most abundant element therein, after oxygen and silicon. It makes up about 8% by weight of the Earth's solid surface. Earth's crust occupies less than 1% of Earth's volume Oxygen is 46.6%, Silicon 27.77%, Aluminum is 8.09% and iron is 5%.
759.

Which compound is formed when a Magnesium ribbon is burnt in air?

A. Magnesium Nitrate
B. Magnesium Carbonate
C. Magnesium Oxide
D. Magnesium Nitride
Answer» C. Magnesium Oxide
Explanation: When Magnesium burns air it reacts with oxygen present in air to form magnesium oxide.
760.

Nuclear fission is caused by the impact of.

A. Proton
B. Electron
C. Neutron
D. (1) and (b)
Answer» C. Neutron
Explanation: In such a reaction, free neutrons released by each fission event can trigger yet more events, which in turn release more neutrons and cause more fission.
761.

Interveinal necrotic spots on leaves appear due to –

A. HF injuly
B. SO2 injury
C. NO2 injury
D. O3 injury
Answer» B. SO2 injury
Explanation: Injury caused by sulphur oxides show interveinal necrotic areas that are light tan to white. Uninjured tissue new to the veins remains green.
762.

The pollutant responsible for ozone holes is -

A. CO2
B. SO2
C. CO
D. CFC
Answer» D. CFC
Explanation: Chlorofluorocarbons (CFCs) have been held responsible for the depletion of ozone layer. The manufacture of CFCs has been phased out under the Montreal Protocol, and they are being replaced with other products such as HFCs.
763.

Atomic themy of matter was given by –

A. Avogadro
B. Dalton
C. Newton
D. Pascal
Answer» B. Dalton
Explanation: Democritus first suggested the existence of the atom, but John Dalton (1766- 1844) is credited with the Atomic Theory of Matter. According to Dalton, all matter is made of atoms; atoms are indivisible and indestructible; all atoms of a given element are identical in mass and properties; and compounds are formed by a combination of two or more different kinds of atoms.
764.

The major component in the LPG is -

A. methane
B. butane
C. ethane
D. propane
Answer» B. butane
Explanation: Butanes are highly flammable, colourless, easily liquefied gases. When blended with propane and other hydrocarbons, it is referred to commercially as LPG, for liquified petroleum gas. It is used as a petrol component.
765.

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

A. Chlorofluorocarbons
B. Methane
C. Carbon dioxide
D. Nitrogen
Answer» D. Nitrogen
Explanation: The primary greenhouse gases in the Earth's atmosphere are water vapour, carbon dioxide, methane, nitrous oxide, and ozone. The anthropogenic compound of Chlorofluorocarbons is also a greenhouse gas, with a much higher potential to enhance the greenhouse effect than CO2.
766.

Carbon dioxide is –

A. a reducing agent
B. an oxidising agent
C. a dehydrating agent
D. a bleaching agent
Answer» A. a reducing agent
Explanation: A good reducing agent must be able to donate electrons readily. This means that it must not have very much attraction for electrons. Carbon dioxide is just like any other oxide and can be reduced to its respective elements by applied energy.
767.

An atom of an element has atomic number 17 and mass number 36. The number of neutrons in its nucleus is–

A. 17
B. 19
C. 36
D. 53
Answer» B. 19
Explanation: Mass Number = number of protons (atomic number) + nu.sriber of neutrons. So as per the question, 36= number of neutrons + 17. Number of neutrons= 36 -17= 19
768.

The most reactive among the halogens is

A. Fluorine
B. Chlorine
C. Bromine
D. Iodine
Answer» A. Fluorine
Explanation: Fluorine is one of the most reactive elements in existence, attacking otherwise inert materials such as glass, and forming compounds with the heavier noble gases. It is a corrosive and highly toxic gas. The reactivity of fluorine is such that if used or stored in laboratory glassware, it can react with glass in the presence of small amounts of water to form silicon tetrafluoride (SiF4).
769.

Black lung disease occurs in people working in –

A. Electroplating industry
B. Organic solvents industry
C. Paint manufacturing industry
D. Coal mines
Answer» D. Coal mines
Explanation: Coal worker's pneumoconiosis, colloquially referred to as black lung disease, is a lung disease that results from breathing in dust from coal, graphite, or man-made carbon over a long period of time. Inhaled coal dust progressively builds up in the lungs and is unable to be removed by the body; that leads to inflammation, fibrosis, and in worse cases, necrosis.
770.

NaCI has               .

A. Non-polar bonds
B. Polar covalent bonds
C. Metallic bonds
D. Ionic bonds
Answer» D. Ionic bonds
Explanation: Sodium Chloride, NaCl. The classic case of ionic bonding, the sodium chloride molecule forms by the ionization of sodium and chlorine atoms and the attraction of the resulting ions.
771.

The metal used to recover copper from a solution of copper sulfate is -

A. Na
B. Ag
C. Hg
D. Fe
Answer» D. Fe
Explanation: The metal used to recover copper from a solution of copper sulfate is Fe.
772.

Which of the following is also known as 'Galena'?

A. Lead sulphate
B. Lead oxide
C. Lead sulphide
D. Calcium sulphate
Answer» C. Lead sulphide
Explanation: Galena, also called lead glance, is the natural mineral form of lead sulfide. It is the most important ore of lead and an important source of silver.
773.

Which of the following elements has the lowest melting point?

A. Sodium
B. Tin
C. Radon
D. Radium
Answer» C. Radon
Explanation: Among the given elements, Radon has the lowest melting point of-71°Celsius. The melting point of other elements are as follows: Sodium: 98° C; Tin 232° C; Radium: 700°C
774.

The oxidation number of nickel in K4[Ni(CN)4] is -

A. Zero
B. +4
C. -4
D. +8
Answer» A. Zero
Explanation: The oxidation number of nickel in K4[Ni(CN)4] is zero.
775.

The rusting of iron is a/an -

A. physical change
B. electrochemical change
C. electrical change
D. None of the above
Answer» B. electrochemical change
Explanation: When iron is exposed to air and moisture, its surface gradually corroded and converted into a brown mass. The rusting of iron is due to the formation of hydrated ion. Rusting is an electro-chemical process.
776.

Ethanol containing 5% water is known as –

A. Dilute alcohol
B. Power alcohol
C. Rectified spirit
D. Absolute alcohol
Answer» C. Rectified spirit
Explanation: A rectified alcohol is highly concentrated ethanol which' has been purified by means of repeated distillation, a process that is called rectification. It typically contains 95% alcohol by volume and 5% water. Normally, ethanol with 5% water is known as pure alcohol.
777.

Stains of rust on clothes can be removed by –

A. Oxalic acid
B. Petrol
C. Alcohol
D. H2O2
Answer» A. Oxalic acid
Explanation: Rust stains can be a challenge to remove because the stain consists of tiny iron oxide particles. Acidic solutions work best for these stains. The important ingredient in these removers is an acid - usually oxalic or hydrofluoric acid. The remover ingredients combine with the iron and loosen it from the fabric, then hold it in suspension in the wash water.
778.

If a solution turns blue litmus red, its pH is likely to be :

A. 7
B. 8
C. 9
D. 6
Answer» D. 6
Explanation: An acidic solution turns blue litmus red. On the pH scale, acids have values less than 7, whereas bases have values greater than 7. Solutions with pH equal to 7 are neutral in nature. Therefore the pH of the given solution is likely to be 6.
779.

An element with an atomic number of 17 is -

A. an alkali metal
B. a rare gas
C. a halogen gas
D. a transition metal
Answer» C. a halogen gas
Explanation: Chlorine has atomic number of 17. It is a halogen gas along with fluorine (F), bromine (Br), iodine (I), and astatine (At).
780.

Consider the following and select the right option.

A. Stomach - Hydrochloric acid
B. Ant - formic acid
C. Both are right
D. Both are wrong
Answer» C. Both are right
Explanation: Hydrochloric acid is naturally found in the gastric juices of the stomach. It is secreted through the parietal cells of the stomach.
781.

As which one of the following, does carbon occur in its purest form in nature?

A. Carbon black
B. Graphite
C. Diamond
D. Coal
Answer» C. Diamond
Explanation: The purest form of carbon is neither diamond nor graphene or graphite . It is 'Fullerene' , the purest form of carbon.
782.

Which among the following is a covalent compound?

A. Calcium chloride
B. Magnesium fluoride
C. Sodium chloride
D. Carbon tetrachloride
Answer» D. Carbon tetrachloride
Explanation: Ionic compounds are made up of a metal and non-metal, and covalent compounds are made up of two nonmetals
783.

The highest volume of gases in lower atmosphere is comprised of -

A. Hydrogen
B. Carbon dioxide
C. Oxygen
D. Nitrogen
Answer» D. Nitrogen
Explanation: There are a number of atmospheric gases which make up air. In the lower atmosphere or troposphere, the main gases are nitrogen and oxygen, which make up 78% and 21% of the volume of air respectively. The remaining 1% of the atmospheric gases is made up of trace gases.
784.

The alkoloid naturally found in coffee, cocoa and cola nut is –

A. Cocaine
B. Morphine
C. Tannin
D. Caffeine
Answer» D. Caffeine
Explanation: Caffeine (C8H10N4O2) is a bitter alkaloid found especially in coffee, tea, cacao, and kola nuts. It is used medicinally as a stimulant and diuretic.
785.

The metal used for making air crafts and rockets is –

A. Lead
B. Aluminium
C. Nickel
D. Copper
Answer» C. Nickel
Explanation: Nickel-based super alloys are an unusual class of metallic materials with an exceptional combination of high temperature strength, toughness, and resistance to degradation in corrosive or oxidizing environment. These materials are widely used in aircraft and power-generation turbines, rocket engines, etc.
786.

At what temperature is the density of water the maximum?

A. 2°C
B. 4°C
C. 0°C
D. 1°C
Answer» B. 4°C
Explanation: An especially notable irregular maximum density is that of water, which reaches a density peak at 3.98 °C (39.16 °F).
787.

Soil having high content of aluminum and iron oxide is also known as -

A. meadow soil
B. pedalfer soil
C. chernozen soil
D. podzol soil
Answer» B. pedalfer soil
Explanation: Pedalfer soil is composed of aluminum and iron oxides. It is a subdivision of the zonal soil order comprising a large group of soils in which sesquioxides increase relative to silica during soil formation.
788.

Chile saltpeter is the common name of:

A. Sodium nitrate
B. Potassium nitrite
C. Potassium nitrate
D. Sodium nitrite
Answer» A. Sodium nitrate
Explanation: Sodium Nitrate (NaNO3) is also known as Chile saltpeter or Peru saltpeter (due to the large deposits found in the Atacama desert in these countries) to distinguish it from ordinary saltpeter, potassium nitrate. Also known as soda niter, it is used in the production of fertilizers, pyrotechnics and smoke bombs, glass and pottery enamels, food preservatives, and solid rocket propellant.
789.

The gas liberated in the Bhopal gas tragedy was:

A. Pheynl isocynate
B. Acetylene
C. Ethylene
D. Methyl isocynate
Answer» D. Methyl isocynate
Explanation: The Bhopal gas tragedy involved the leakage of poisonous methyl isocyanate (MIC) gas and other chemicals at the Union Carbide India Limited (UCIL) pesticide plant in Bhopal, Madhya Pradesh, on the night of 2-3 December 1984. It is considered the world's worst industrial disaster.
790.

Which of the following is not a gaseous air pollutant?

A. Oxides of nitrogen
B. Hydrocarbon
C. Smoke
D. Oxides of sulphur
Answer» B. Hydrocarbon
Explanation: The gaseous air pollutants of primary concern in urban settings include sulfur dioxide, nitrogen dioxide, and carbon monoxide; these are emitted directly into the air from the combustion of fossil fuels. Smoke a collection of airborne solid and liquid particulates and gases emitted when a material undergoes combustion, is also a pollutant. Hydrocarbon is an organic compound consisting entirely of hydrogen and carbon.
791.

At room temperature, the metal that remains liquid is:

A. Mercury
B. Platinum
C. Lead
D. Zinc
Answer» A. Mercury
Explanation: Mercury is the only metal that is a liquid at normal temperatures and pressure. At room temperatureand pressure, mercury neither readily share valence electrons with other atoms nor interact with each other to form a structure or lattice to become a solid. Infact, mercury is the only metal that doesn't form diatomic molecules in the has phase.
792.

The chemical name or Quartz is –

A. Calcium oxide
B. Calcium phosphate
C. Sodium phosphate
D. Sodium silicate
Answer» D. Sodium silicate
Explanation: Quartz is a compound of one part silicon and two parts of oxygen, silicon dioxide, SiO2. Quartz is the most abundant silica mineral. It is used in a number of industries, the important being glass, foundry, sodium silicate, silicon alloys, etc. The various grades of sodium silicate are characterized by their SiO2:Na2O weight ratio.
793.

The depletion in Ozone layer is caused by -

A. Nitrous oxide
B. Carbon dioxide
C. Chlorofluorocarbons
D. Methane
Answer» C. Chlorofluorocarbons
Explanation: Chlorofluorocarbons (CFCs), also known as Freon, cause the breakdown of the ozone layer that protects the earth from the sun's ultraviolet (UV) radiation. In the upper atmosphere, the UV-induced breakdown of CFCs releases free, highly reactive chlorine and bromine atoms that lead to the breakdown of the stratospheric ozone layer. Owing to ozone depletion in the upper atmosphere, CFCs have been phased out under the Montreal Protocol of 1987.
794.

Which one of the following elements is essential for the construction of nuclear reactors?

A. Cobalt
B. Nicke
C. Zirconium
D. Tungsten
Answer» C. Zirconium
Explanation: Zirconium is an essential element for the construction of nuclear reactors.
795.

The isotope atoms differ in -

A. number of neutrons
B. atomic number
C. number of electrons
D. atomic weight
Answer» A. number of neutrons
Explanation: Important to note that isotope atoms have same atomic number.
796.

This substance is sweet-smelling and is used in making perfumes and flavouring agents. It is called-

A. Sodium ethanoate
B. Lime water
C. Hydrogencarbonates
D. Ester
Answer» D. Ester
Explanation: The correct answer is Ester. An ester is a sweet-smelling substance, used in making perfumes and flavouring agents.
797.

An acid is a substance which

A. Donates a proton
B. Accepts an electron
C. Give H+ in water
D. All
Answer» D. All
Explanation: An acid is a chemical substance whose aqueous solutions are characterized by a sour taste, the ability to turn blue litmus red and the ability to react with bases and certain metals to form salts.
798.

Two electrons in an orbital are differentiated by which of the following?

A. Magnetic quantum number
B. Spin quantum number
C. Principal quantum number
D. Azimuthal quantum number
Answer» B. Spin quantum number
Explanation: Spin quantum number is the is the fourth quantum number that differentiates two electrons in the same orbital. The Pauli exclusion principle states that "no two electrons in an atom can have the same four quantum numbers. This means that no two electrons can have the same state in an atom. Each electron must have a different spin or occupy a different shell from any other.
799.

The most abundant element in the earth's atmosphere is –

A. Argon
B. Nitrogen
C. Oxygen
D. Krypton
Answer» B. Nitrogen
Explanation: The most abundant gas in the Earth's atmosphere is nitrogen. Nitrogen makes up 78 percent of the Earth's atmosphere, and it is a permanent gas, which means that its percentage does not change on a daily basis. The rest of the atmosphere is made up of 21 percentoxygen, 0.9 percent argon and 0.1 percent trace gases.
800.

Chemical composition of cement is –

A. Limestone and Clay
B. Limestone, Clay and Gypsum
C. Limestone and Gypsum
D. Clay and Gypsum
Answer» B. Limestone, Clay and Gypsum
Explanation: The two important raw materials used for the preparation of cement are : • Limestone : The chemical formula of limestone is CaCO3 and it is used in the manufacture of cement just to provide CaO.
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