Science Environment And Technology – Yearwise Questions – Chemistry – W.B.C.S. Mains Examination.

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WBCS Main Question Paper – 2019

1. The function of heavy water in a nuclear reactor is to
   (A) cool down the reactor.
   (B) stop the nuclear reaction.
   (C) slow down the speed of neutrons.
   (D) increase the speed of neutrons
2. The general molecular formula for disaccharide is
   (A) C10H20O10
   (B) C12H22O11
   (C) C12H20O10
   (D) C12H22O10
3. The pH for drinking water should be between
   (A) 5 – 6
   (B) 6 – 6.5
   (C) 6.5 – 7.5
   (D) 8 – 9
4. Oxidation state of Oxygen in F2O is
   (A) -1
   (B) +1
   (C) +2
   (D) -2
5. The homologue of ethyne is
   (A) C2H2
   (B) C2H6
   (C) C3H4
   (D) C3H8
6. Which is used in alcoholic beverages?
   (A) Ethanol
   (B) Methanol
   (C) Phenol
   (D) Glycerol
7. For the radioactive nuclei that undergo either α or ß decay, which one
   of the following cannot occur?
   (A) Isobar of original nucleus is produced.
   (B) Isotope of the original nucleus is produce
   (C) Nuclei with higher atomic number than that of the original nucleus is produced.
   (D) Nuclei with lower atomic number than that of the original nucleus is produced.
8. Which of the following does not have coordinate bond?
   (A) SO2
   (B) HNO2
   (C) HNO3
   (D) H2SO3
9. Which one of the following is wrong about molecularity of a reaction?
   (A) It may be whole number or fractional.
   (B) It is calculated from reaction mechanism.
   (C) It is the number of molecules of the reactants taking part in a single step chemical reaction.
   (D) It is always equal to the order of elementary reaction.
10. The unit of radioactivity is
    (A) Co
    (B) Ci (SI unit – curie )
    (C) Cr
    (D) Cq
11. The temporary hardness of water is caused by
    (A) Oxides
    (B) Bicarbonates
    (C) Chlorides
    (D) Sulphates
12. During the emission of a positron from a nucleus, the mass number of
    the daughter element remains the same but the atomic number
    (A) is decreased by 1 unit
    (B) is decreased by 2 units
    (C) is increased by 1 unit
    (D) remains unchanged
13. SiO2 is reacted with Sodium Carbonate. What is the gas liberated?
    (A) CO2
    (B) CO
    (C) O2
    (D) O3
14. In gamma ray emission from a nucleus
    (A) only proton number changes.
    (B) only neutron number changes.
    (C) there is no change in the proton number and neutron number.
    (D) Both the proton number and the neutron number change.
15. In radioactive decay process, the negatively charged emitted ß particles are
    (A) the electrons present inside the nucleus.
    (B) the electrons produced as a result of the decay of neutrons inside the nucleus.
    (C) the electrons produced as a result of collisions between atoms.
    (D) None of the above
16. What is the main energy generation process in the Sun?
    (A) Nuclear fission
    (B) Nuclear radioactive decay
    (C) Gravitational energy
    (D) Nuclear fusion
17. Formation of stars begin from the following two gases:
    (A) Hydrogen and Nitrogen
    (B) Nitrogen and Oxygen
    (C) Oxygen and Hydrogen
    (D) Hydrogen and Helium
18. Which of the following is a liquid form of aerosol?
    (A) Fume
    (B) Dust
    (C) Mist
    (D) Smoke

WBCS Main Question Paper – 2018

1. The organic compound used as food preservative :
   a) Methyl salicylate
   b) Sodium benzoate
   c) Sodium acetate
   d) Sorbitol
2. The isotope used in cancer therapy
   a) Co58
   b) C14
   c) I131
   d) Co60

3.Formula of baking powder is
a) NaHCO3
b) Na2CO3, 10H2O
c) Na2B4O7 ,10H2O
d) CaSO4, 2H2O

4. Carbon atom in benzene molecule is
   a) sp hybridised
   b) sp2 hybridised
   c) sp3 hybridised
   d) Not hybridised
5. The carbolic acid is
   a) benzoic acid
   b) phthalic acid
   c) phenol
   d) H2CO3
6. Which of the following heterocyclic compound is not aromatic ?
   a) Pyridiene
   b) Pyrole
   c) Furan
   d) Piperidine
7. The oxide functioning as Piezoelectric substance :
   a) Al2O3
   b) ZrO2
   c) TiO2
   d) BaTiO3
8. Which of the following salt is dissolved in aqueous ammonia ?
   a) PbCl2
   b) Cu(OH)2
   c) AgI
   d) Al(OH)2
9. The reaction of Cl2 + 2NaOH = NaCl + NaOCl + H2O is a
   a) subsitution reaction
   b) elminiation
   c) neutralisation reaction
   d) disproportionation reaction
10. Which of the following is used as high temperature lubricant ?
    a) Mica
    b) Asbestos
    c) Graphite
    d) Silicones
11. Graphite is used in nuclear reactor as
    a) Lubricant
    b) Fuel rod
    c) Control rod
    d) Coating
12. Which is the hardest material of the following ?
    a) Corundum
    b) Diamond
    c) SiC
    d) B4C
13. NH3 gas is dried by using
    a) Conc. H2SO4
    b) P2O5
    c) Fused CaCl2
    d) Qucik Lime
14. Black color of old oil painting can be cleaned by
    a) Cl2 water
    b) H2O2
    c) Nascent hydrogen
    d) Oxalic acid
15. In the contact process for the manufacture of H2SO4, V2O5 function as
    a) oxidising agent
    b) reducing agent
    c) catalyst
    d) neutralising agent
16. A thick mass of cement, sand and water is called
    a) Concrete
    b) RCC
    c) Mortar
    d) Monolith
17. Bronze is the alloy of
    a) Copper and Zinc
    b) Copper and Tin
    c) Coper and Nickel
    d) Zinc and Tin
18. The process of very slow cooling in metallurgy is known as
    a) Quenching
    b) Annealing
    c) Hardening
    d) Cold working
19. The chemical bonding in diamond is
    a) Covalent
    b) Ionic
    c) Coordinate
    d) Metallic
20. For deriving p-type semiconductor, the element to be mixed with Si :
    a) Phosphorous
    b) Aluminum
    c) Arsenic
    d) None of the above
21. Which of the following is an artificial rubber ?
    a) Isoprene
    b) Chloroprene
    c) Neoprene
    d) Teflon
22. The metal extracted from hematite using blast furnace:
    a) Zn
    b) Cu
    c) Al
    d) Fe
23. The connecting material in solar panels is
    a) Si
    b) Silver
    c) Selenium
    d) CuH.O
24. Phenol and Formaldehyde are used for the production of
    a) Caprolactum
    b) Bakelite
    c) PVC
    d) Nylon 6
25. Which of the following fuel produces hottest flame on ignition with oxygen ?
    a) C2H2
    b) H2
    c) Cyanogen
    d) Butane
26. When electricity is passed through an electrolyte it undergoes
    a) physical changes
    b) chemical changes
    c) no physical or chemical changes
    d) dissociation into cation and anion
27. Temperature (K) and volume (V) relationship of a gas undergoing
    adiabatic expansion (y= Cp/Cv)
    a) TV = Constant
    b) TV y = Constant
    c) TVy-1 = Constant
    d) T yV = Constant
28. The crystal having cell dimensions, a ¹ B ¹ c, a = b = g = 90º has
    structure
    a) Tetragonal
    b) Orthorhombic
    c) Triclnic
    d) Monoclinc
29. Nucleons are the number of
    a) protons present in the nucleus
    b) neutrons present in the nucleus
    c) sum of protons and neutrons in the nucleus
    d) total protons, neutrons and electrons in the atom
30. Which of the following possesses zero dipole moment?
    a) NH3
    b) CCl4
    c) BF3
    d) H2O
31. If an enzyme fixes nitrogen in plant by evolving H2, the number of
    electrons and protons associated with respectively are
    a) 6 and 6
    b) 6 and 8
    c) 8 and 8
    d) 8 and 6
32. Water becomes hard due to presence of soluble salt of ion
    a) Al+3
    b) Na
    c) K
    d) Ca2+
33. At 0 K, fluids are assumed to have
    a) minimum entropy
    b) maximum entropy
    c) zero entropy
    d) a fixed value of entropy
34. Water has maximum density at
    a) room temperature
    b) 0°C
    c) 4°C
    d) 100°C
35. The water used in nuclear reactor is called
    a) Hard water
    b) Heavy water
    c) Nuclear water
    d) Critical water
36. The quantity remaining constant in isothermal expansion of an ideal gas:
    a) Heat content
    b) Internal energy
    c) Pressure
    d) Pressure and Temperature
37. Water gas is extremely poisonous due to presence of
    a) N2
    b) CO
    c) H2
    d) H2S
38. The quality of gasolene is expressed in terms of
    a) Octane number
    b) Cetane number
    c) Gold number
    d) Reynold’s number
39. Which of the following is a complex salt?
    a) A1(NO3)3,9H2O
    b) K4[Fe(CN)6]
    c) KSO4, Cr(SO4)3, 24 H2O
    d) Ca(OCl)Cl
40. Which compound is used as rocket fuel?
    a) Polybutadiene
    b) N2H4
    c) N3H
    d) Both (A) and (B)
41. When molten sulphur is poured suddenly into water, it takes the form of
    a) milk of sulphur
    b) flower of sulphur
    c) plastic sulphur
    d) colloidal sulphur
42. The compound used in safety matches is
    a) P4
    b) PCl3
    c) P2O5
    d) P4S3
43. Permanent hardness of water is estimated by
    a) Conductometne titration
    b) lodometric titration
    c) Acid-base titration
    d) Complexometric EDTA titration
44. The gas used to extinguish fire:
    a) CO2
    b) Ar
    c) N2
    d) CO

WBCS Main Question Paper – 2017

1. Crude petroleum is converted to number of hydrocarbon products by
   (A) Fractional distillation
   (B) Thermal cracking
   (C) Steam distillation
   (D) None of the above
2. The Redox indicator used in volumetric titration of
   (A) Bromophynol Blue
   (B) Methyl Orange
   (C) Barium diphenyl amine sulphonate
   (D) Solochrome black-T
3. Gas released during Bhopal tragedy was :
   (A) Sodium isothiocyanate
   (B) Ethyl isothiocyanate
   (C) Potassium isothiocyanate
   (D) Methyl isothiocyanate
4. Natural rubber is a polymer of
   (A) Isoprene
   (B) Styrene
   (C) Vinyl acetate
   (D) Butadiene
5. Tollens reagent is

(A) Alkaline mercuric chloride
(B) Alkaline potassium permanganate
(C) Ammoniacal silver nitrate
(D) Ammonium citrate

6. Paraffin wax is
   (A) Ester
   (B) Alcohol
   (C) unsaturated hydrocarbons
   (D) saturated hydrocarbons
7. Which one of the following gas is used for artificial ripening of fruits ?
   (A) Methane
   (B) Acetylene
   (C) Ethylene
   (D) Propane
8. Which one of the following materials does not show piezoelectric
   behavior ?
   (A) Quartz
   (B) Rochelle salt
   (C) Rutile
   (D) Barium titanate
9. The BET study is performed to measure
   (A) particle size distribution
   (B) specific surface area
   (C) dielectric constant
   (D) specific gravity
10. The potash feldspar is known as
    (A) Orthoclase
    (B) Albite
    (C) Anorthite
    (D) Dickite
11. The acid employed for etching of glass is
    (A) HCl
    (B) HNO3
    (C) Aqua-regia
    (D) HF
12. The melting point of silica is
    (A) 1710° C
    (B) 2050°C
    (C) 2300°C
    (D) 1810°C
13. Which one of the following remains in solid state at room temperature
    ?
    (A) Cl2
    (B) F2
    (C) I2
    (D) Br2
14. Mars gas contains
    (CO2 – 95.32%, N2 – 2.6%, Ar – 1.9%)
    (A) CO2
    (B) CH4
    (C) N2
    (D) C2H6
15. Which one of following constitutes the common glass composition ?
    (A) Sodium Silicate
    (B) Calcium Silicate
    (C) Calcium and Sodium Silicate
    (D) Lead Silicate
16. Stainless steel contains
    (A) Fe + Cr + Ni
    (B) Fe + Ni + Cu
    (C) Fe + Mn + Cr
    (D) Fe + Co + Ni
17. Iron loses its magnetic property at
    (1043 K / 7700 C)
    (A) Melting point
    (B) Curie point
    (C) 1000°C
    (D) Boiling point
18. Bell metal is an alloy of
    (A) Cu + Sn
    (B) Cu + Zn
    (C) Cu + Ni
    (D) Cu + Mn
19. Which element has the greatest ductility property ?
    (A) Cu
    (B) Ag
    (C) Au
    (D) Pt
20. Aluminum is extracted from bauxite by
    (A) Bayer’s process
    (B) Downs process
    (C) Solvay process
    (D) Oswald process
21. The main radioactive element of pitch blende ore is
    (A) Ra
    (B) Th
    (C) U
    (D) Po
22. The maximum consumption of refractories involves in
    (A) Glass Industries
    (B) Iron and Steel Plants
    (C) Cement Plants
    (D) Petroleum Industries
23. The most common element in the universe is
    (A) Fe
    (B) Ca
    (C) Al
    (D) Si (28%)
24. The base composition of whiteware body contains
    (A) Clay, Quartz and Talc
    (B) Quartz, Clay and Feldspar
    (C) Talc, Bauxite and Wollastonite
    (D) Clay, Gypsum and Feldsper
25. Which of the following metals do not form amalgam ?
    (A) Iron
    (B) Sodium
    (C) Zinc
    (D) Magnesium
26. Jam-jelly can be preserved by adding small percentage of
    (A) HCHO
    (B) EDTA
    (C) Sodium benzoate
    (D) CH3COOH
27. Reverse of swelling of gel is known as
    (A) Syneresis
    (B) Intestine
    (C) Adrenal gland
    (D) Blood
28. Which one of the following is not peroxide ?
    (A) BaO2
    (B) Na2O2
    (C) H2O2
    (D) MnO2
29. Atomic packing density in FCC lattice is
    (A) 0.47
    (B) 0.68
    (C) 0.74
    (D) 1.0
30. 44 g of CO2 occupies how many litres of CO2 at STP ?
    (A) 2.4 L
    (B) 2.24 L
    (C) 44 L
    (D) 22.4 L
31. The contact angle of Hg on glass
    (A) = 90°
    (B) >90° (138°)
    (C) <90°
    (D) None of the above
32. Forward chemical reactions happened only if
    (G = Gibbs free energy)
    (A) ΔG = 0
    (B) ΔG > 0
    (C) ΔG < 0
    (D) None of the above
33. Diamond has the Mohs’ scale hardness number of
    (A) 5
    (B) 7
    (C) 10
    (D) 9
34. Bakelite is the product of
    (A) addition polymerization
    (B) condensation polymerization
    (C) co-polymerization
    (D) None of the above
35. High polymerization of ethylene is done by using
    (A) Zeolite catalyst
    (B) V2O5 catalyst
    (C) Zeiglar-Natta catalyst
    (D) Pt-Mo catalyst
36. The isotope used for cancer therapy
    (P-32, Na-24, Sr-89, Cs-137, Sm-153, Ir-192, Ac-225)
    (A) I80
    (B) Co60
    (C) C14
    (D) Ra223
37. Chemical used as insecticide is
    (A) γ-BHC
    (B) Methyl salicylate
    (C) Iodoform
    (D) TNT
38. Number of unpaired electrons present in Cu2+.
    (A) 3
    (B) 5
    (C) 2
    (D) 1
39. Which one of these is not a transitional metal ?
    (A) Ti
    (B) Cr
    (C) Ni
    (D) Zn
40. Diazo-coupling reaction between diazonium salt and naphthol
    produces
    (A) Green dye
    (B) Yellow dye
    (C) Red dye
    (D) Blue dye
41. Chemical formula of Grignard reagent is
    (A) R-Mg-X
    (B) R-Ca-X
    (C) R-Sr-X
    (D) None of the above
42. The structure of α-alumina is
    (A) Trigonal
    (B) Orthorhombic
    (C) Hexagonal
    (D) Cubic
43. The isotope used as fuel in nuclear power plant is
    (A) U235
    (B) U238
    (C) U233
    (D) U239
44. Which of the following behaves as chemically most active non-metal ?
    (A) F2 (Fluorine)
    (B) He
    (C) N2
    (D) O2
45. A mixture of carbon monoxide and hydrogen is called
    (A) natural gas
    (B) water gas
    (C) Producer gas
    (D) None of the above
46. Which fuel has the maximum calorific value ?
    (Hydrogen highest – 150 KJ/g)
    (A) Charcoal
    (B) Kerosene
    (C) Wood
    (D) LPG (50 KJ/g)
47. The hydrolysis of cane sugar is catalyzed by
    (A) H+
    (B) Enzymes
    (C) Mineral acid
    (D) All of the above
48. The catalyst used in the hydrogenation of oils is
    (A) V2O5
    (B) Ni
    (C) Fe
    (D) Pt
49. Hydrochloric acid is also known is
    (A) Chloric acid
    (B) Muriatic acid
    (C) Galic acid
    (D) Picric acid
50. Which one of the following element is essential for the construction of
    nuclear reactors ?
    (A) Tungsten
    (B) Platinum
    (C) Cobalt
    (D) Zirconium
51. Martensitic steel has following crystal structure
    (body-centered tetragonal crystal structure)
    (A) BCC
    (B) FCC
    (C) BCT
    (D) HCP

WBCS Main Question Paper – 2016

1. A gas is enclosed in a container which is then placed on a fast moving
   train. The temperature of the gas –
   (A) falls
   (B) rises
   (C) remains unchanged
   (D) becomes unsteady
2. In nuclear reaction, there is conservation of-
   (A) energy only
   (B) momentum only
   (C) mass, energy and momentum
   (D) mass only
3. Particles which can be added to the nucleus of atom without changing
   its chemical properties are —
   (A) electron
   (B) protons
   (C) neutrons
   (D) α-particles
4. The number of unpaired electrons in Mn2+ is –
   (A) 1
   (B) 3
   (C) 4
   (D) 5
5. A radioactive decay process has a half-life of 4 yr. The amount of the
   reactant remaining after 12 years is
   (A) 10%
   (B) 12.5%
   (C) 25%
   (D) 87.5%

6.Radioactive substance used in dating geological object is –
(A) C – 12
(B) C – 11
(C) C – 14
(D) None of the above

7. The patient is asked to drink barium sulphate (BaSO4) for examining
   the stomach by X-rays because X-rays are
   (A) less absorbed by heavy atoms
   (B) more absorbed by heavy atoms
   (C) reflected by heavy atoms
   (D) refracted by heavy atoms
8. Which one of the following is not radioactive ?
   (A) Astatine
   (B) Francium
   (C) Tritium
   (D) Zirconium

WBCS Main Question Paper – 2015

1. Which of the following is natural polymer ?
   (condensation polymer)
   (A) Terylene
   (B) Orion
   (C) Starch
   (D) Dacron
2. Marsh gas is
   (CH4 + H2S + CO2)
   (A) Methane
   (B) Ethane
   (C) Ethylene
   (D) None of the above
3. In the metallurgy of iron, the material obtained from bottom of the blast
   furnace is
   (A) Slag
   (B) Pig iron
   (C) Cast iron
   (D) Wrought iron
4. The main ore of aluminum is
   (A) Bauxite
   (B) Alumina
   (C) Potash-alum
   (D) Cryolite
5. Which one is the unit of radio activity ?
   (A) Curie
   (B) Tasla
   (C) Henry
   (D) Uranium
6. When a lead storage cell is charged
   (A) Sulphuric Acid is consumed
   (B) Sulphuric Acid is formed
   (C) Lead sulphate is formed
   (D) Lead is consumed
7. The temperature above which a real gas cannot be liquefied is known
   as
   (A) Critical temperature
   (B) Boyle temperature
   (C) Inversion temperature
   (D) None of the above
8. Carnalite on electrolysis gives
   A) Ca & Cl2
   B) Na & CO2
   C) Al & Cl2
   D) Mg & Cl2
9. Which one is correct sequence in increasing order of molecular weights
   of the hydrocarbons?
   (A) Methane, ethane, propane and butane
   (B) Propane, butane, ethane and methane
   (C) Butane, ethane, propane and methane
   (D) Butane, propane, ethane and methane
10. Which one of the following is known as RDX?
    (Royal Demolition eXplosive)
    (A) Cyanohydrin
    (B) Dextran
    (C) Cyclohexane
    (D) Cyclonite
11. Which one of the following does not contain silver?
    (A) Horn silver
    (B) German silver
    (C) Ruby silver
    (D) Lunar Caustic
12. Which one of the following is also called a stranger gas?
    (A) Argon
    (B) Neon
    (C) Xenon
    (D) Nitrous oxide
13. Which one of the following is used as an explosive?
    (A) Phosphorus trichloride
    (B) Mercuric oxide
    (C) Graphite
    (D) Nitroglycerine
14. Which one of the following sets of elements was primarily responsible for the origin of life on the Earth?
    (A) Hydrogen, Oxygen, Sodium
    (B) Carbon, Hydrogen, Nitrogen
    (C) Oxygen, calcium, Phosphorus
    (D) Carbon, Hydrogen, Potassium
15. Which one among the following is called Philosopher’s wool?
    (A) Zinc Bromide
    (B) Zinc Nitrate
    (C) Zinc Oxide
    (D) Zinc Chloride
16. D.D.T was invented by

(A) Paul Muller
(B) La Mark
(C) Pavlov
(D) Darwin

17. The total of a given mass of a gas at a given temperature depends on
    (A) Pressure
    (B) Volume
    (C) Density
    (D) Temperature
18. In a nuclear reactor the chain reaction is controlled by introducing
    (A) Iron rods
    (B) Cadmium rods
    (C) Graphite rods
    (D) Platinum rods
19. When water is heated from 0°C to 10°C. Its Volume
    (A) Increases
    (B) Decreases
    (C) Does not change
    (D) First decreases then increases
20. Which of the following is a good nuclear fuel?
    (U-233, U-235 & P-239)
    (A) Uranium-238
    (B) Neptunium-239
    (C) Plutonium-239
    (D) Thorium-236
21. Gunpowder consists of a mixture of
    (A) sand and TNT
    (B) Sulphur, Sand and charcoal
    (C) Nitrate, Sulphur and Charcoal
    (D) TNT and charcoal
22. Most glass contain about 71 % by weight of
    (A) Silicon dioxide
    (B) Carbon dioxide
    (C) Sulphur dioxide
    (D) Calcium carbonate

WBCS Main Question Paper – 2014

1. The reaction that takes place inside the Sun to power it is
   (A) Fission
   (B) Fusion
   (C) Oxidation
   (D) Decay
2. The following substance is not an oxidizing agent
   (A) Ozone
   (B) Chloride
   (C) Potassium
   (D) Fluorine
3. The most electronegative among the elements sodium, potassium,
   oxygen and fluorine is
   (A) sodium
   (B) potassium
   (C) oxygen
   (D) fluorine
4. The technique of barium X-ray utilizes the following property of barium
   sulphate
   (A) It is opaque to X-rays
   (B) It is radioactive
   (C) It is transparent to X-rays
   (D) It is easily absorbed by tissues
5. Naphthalene has the formula
   (A) C6H6
   (B) C10H8
   (C) C12H10
   (D) C12H12
6. Which of the following uranium isotopes is mostly used in nuclear
   reactors and nuclear weapons ?
   (A) Uranium – 232
   (B) Uranium – 234
   (C) Uranium – 235
   (D) Uranium – 238
7. The basic molecule binds with other molecules to form a polymer is
   called
   (A) macromolecule
   (B) monomolecule
   (C) monomer
   (D) monolith
8. Epoxy resins are used as
   (A) detergents
   (B) insecticides
   (C) adhesives
   (D) moth repellents
9. The half-life period of an isotope is 2 hours. After 6 hours the fraction
   of the initial quantity of the isotope left behind will be
   (A) 1/6
   (B) 1/8
   (C) 1/12
   (D) 1/16

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