Chemistry (Science) - WBCS Main Paper

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Chemistry - Science - WBCS Main Question Paper

wbcs main chemistry question paper

WBCS Main Question Paper – 2020

Diamond and graphite are allotropes of

(A) Iron

(B) Gold

(C) Carbon

(D) Copper

Number of valence electrons in Cl^– ion are

(A) 16

(B) 8

(D) 18

The chemical formula C₂H₅OH stands for

(ethyl alcohol)

(A) Methane

(B) Methanol

(D) Ethanol

Fe₂O₃+ 2Al → Al₂O₃+ 2Fe.

This reaction is an example of a

(A) combination reaction

(B) double displacement reaction

(D) displacement reaction

The pH value of a neutral solution is

(A) 3

(B) 5

(C) 7

(D) 9

The first periodic table was given by

(Russian chemist, 1869)

(A) Mendel

(B) Mendeleev

(D) Dalton

Which of the following is a wrong description of binding energy of a nucleus ?

(A) It is the energy required to break a nucleus into its constituent nucleons.

(B) It is the energy made available when free nucleons combine to form a nucleus.

(D) It is the sum of the kinetic energy of all the nucleons in the nucleus.

The number of neutrons in Hydrogen nucleus is

(A) 0

(B) 1

(D) 3

How many atoms are there in one mole atom of an element ?

(SI unit)

(A) 5.015 x 10¹⁵

(B) 6.022 x 10²³

(D) 6.539 x 10²⁰

In one average-life of radioactive decay

(decay by 63.2%)

(A) half the active nuclei decay.

(B) less than half the active nuclei decay.

(C) more than half the active nuclei decay.

(D) all the nuclei decay.

What is the typical size of an atom ?

(A) 1 meter

(B) 10^-2 meter

(D) 10^-10 meter

Which of the following statements is not a correct statement about the trends when going from left to right across the periods of Periodic Table ?

(Ionisation energy)

(A) The elements become less metallic in nature.

(B) The number of valence electrons increases.

(C) The atoms lose their electrons more easily.

(D) The oxides become more acidic.

What happens when dilute hydrochloric acid is added to iron fillings ?

(2HCl + Fe → FeCl₂ + H₂)

(A) Hydrogen gas and iron chloride are produced.

(B) Chlorine gas and iron hydroxide are produced.

(D) Iron salt and water are produced.

Energy generation in stars takes place mainly via

(D + T → He + n)

(A) nuclear fission

(B) chemical displacement reaction

(C) nuclear fusion

(D) chemical additive reaction

The metal which can be easily cut with a knife –

(Na)

(A) Paper

(B) Silver

(C) Sodium

(D) Gold

Two isotopes have the same

(A) mass number

(B) difference between neutron number and proton number

(D) proton number

In the Rutherford experiment towards the discovery of the atomic nucleus the target used was

(1911)

(A) Gold

(B) Silver

(D) Copper

Write the chemical formulae of Magnesium chloride.

(A) MgCl

(B) MgCl₂

(D) MgCl₄

Electron was discovered by

(1897, English Physicist)

(A) Bohr

(B) Thomson

(D) Heisenberg

The temperature, on centigrade scale, at which the density of water is maximum –

(A) 100°

(B) 44°

(C) 4°

(D) 0°

Which of the following parameters is the same for molecules of all gases at a given temperature ?

(A) Mass

(B) Speed

(D) Kinetic energy

70. A nucleus has 6 protons and 8 neutrons. The nucleus emits two α particles. How many protons and neutrons will be left in the nucleus ?

(A) 2 and 4

(B) 2 and 2

(D) 5 and 7

128. Flame photometry is a suitable method for the determination of

(A) heavy metals

(B) dissolved gases

(D) alkali metals

160. Ultrafiltration can remove

(A) suspended solids

(B) bacteria

(D) All of the above

WBCS Main Question Paper – 2019

9. The pH of drinking water should be between

(A) 5 – 6

(B) 6 – 6.5

(D) 8 – 9

105. The function of heavy water in a nuclear reactor is to

(A) cool down the reactor.

(B) stop the nuclear reaction.

(D) increase the speed of neutrons

106. The general molecular formula for disaccharide is

(A) C10H20O10

(B) C12H22O11

(D) C12H22O10

115. Which of the following configurations corresponds to element of highest ionization energy?

(A) 1S2, 2s1

{B) 1s2, 2s2, 2p3

(D) 1s2, 2s2, 2p6, 3s1

116. Oxidation state of Oxygen in F2O is

(A) -1

(B) +1

(D) -2

117. Which of the following does not have coordinate bond?

(A) SO2

(B) HNO2

(D) H2SO3

118. The homologue of ethyne is

(A) C₂H₂

(B) C₂H₆

(D) C₃H₈

119. Which is used in alcoholic beverages?

(A) Ethanol

(B) Methanol

(D) Glycerol

138. 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

(D) Nuclei with lower atomic number than that of the original nucleus is produced.

140. 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

(D) remains unchanged

141. 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.

(D) It is always equal to the order of elementary reaction.

161. The unit of radioactivity is

(A) Co

(B) Ci(SI unit – curie )

(D) Cq

165. The temporary hardness of water is caused by

(A) Oxides

(B) Bicarbonates

(D) Sulphates

171. SiO2 is reacted with Sodium Carbonate. What is the gas liberated?

(A) CO2

(B) CO

(D) O3

174. In gamma-ray emission from a nucleus

(A) only proton number changes.

(B) only neutron number changes.

(D) Both the proton number and the neutron number change.

175. 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.

(D) None of the above

186. What is the main energy generation process in the Sun?

(A) Nuclear fission

(B) Nuclear radioactive decay

(D) Nuclear fusion

187. Formation of stars begin from the following two gases:

(A) Hydrogen and Nitrogen

(B) Nitrogen and Oxygen

(D) Hydrogen and Helium

177. Which of the following is a liquid form of aerosol?

(A) Fume

(B) Dust

(D) Smoke

WBCS Main Question Paper – 2018

4. The organic compound used as food preservative :

a) Methyl salicylate

b) Sodium benzoate

c) Sodium acetate

d) Sorbitol

5. The isotope used in cancer therapy

a) Co58

b) C14

c) I131

d) Co60

6. Formula of baking powder is

a) NaHCO3

b) Na2CO3, 10H2O

c) Na2B4O7 ,10H2O

d) CaSO4, 2H2O

7. Carbon atom in benzene molecule is

a) sp hybridised

b) sp2 hybridised

c) sp3 hybridised

d) Not hybridised

8. The carbolic acid is

a) benzoic acid

b) phthalic acid

c) phenol

d) H2CO3

9. Which of the following heterocyclic compound is not aromatic ?

a) Pyridiene

b) Pyrole

c) Furan

d) Piperidine

10. The oxide functioning as Piezoelectric substance :

a) Al2O3

b) ZrO2

c) TiO2

d) BaTiO3

11. Which of the following is used as high temperature lubricant ?

a) Mica

b) Asbestos

c) Graphite

d) Silicones

12. Which of the following salt is dissolved in aqueous ammonia ?

a) PbCl2

b) Cu(OH)2

c) AgI

d) Al(OH)2

13. The reaction of Cl2 + 2NaOH = NaCl + NaOCl + H2O is a

a) subsitution reaction

b) elminiation

c) neutralisation reaction

d) disproportionation reaction

14. Graphite is used in nuclear reactor as

a) Lubricant

b) Fuel rod

c) Control rod

d) Coating

15. Black color of old oil painting can be cleaned by

a) Cl2 water

b) H2O2

c) Nascent hydrogen

d) Oxalic acid

16. Which is the hardest material of the following ?

a) Corundum

b) Diamond

c) SiC

d) B4C

17. NH3 gas is dried by using

a) Conc. H2SO4

b) P2O5

c) Fused CaCl2

d) Qucik Lime

18. In the contact process for the manufacture of H2SO4, V2O5 function as

a) oxidising agent

b) reducing agent

c) catalyst

d) neutralising agent

19. A thick mass of cement, sand and water is called

a) Concrete

b) RCC

c) Mortar

d) Monolith

20. Bronze is the alloy of

a) Copper and Zinc

b) Copper and Tin

c) Coper and Nickel

d) Zinc and Tin

21. The process of very slow cooling in metallurgy is known as

a) Quenching

b) Annealing

c) Hardening

d) Cold working

22. The metal extracted from hematite using blast furnace:

a) Zn

b) Cu

c) Al

d) Fe

23. The chemical bonding in diamond is

a) Covalent

b) Ionic

c) Coordinate

d) Metallic

24. For deriving p-type semiconductor, the element to be mixed with Si :

a) Phosphorous

b) Aluminum

c) Arsenic

d) None of the above

30. Which of the following is an artificial rubber ?

a) Isoprene

b) Chloroprene

c) Neoprene

d) Teflon

29. The connecting material in solar panels is

a) Si

b) Silver

c) Selenium

d) CuH.O

32. Phenol and Formaldehyde are used for the production of

a) Caprolactum

b) Bakelite

c) PVC

d) Nylon 6

33. 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

34. Which of the following fuel produces hottest flame on ignition with oxygen ?

a) C2H2

b) H2

c) Cyanogen

d) Butane

38. 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

40. Temperature (K) and volume (V) relationship of a gas undergoing adiabatic expansion(y= Cp/Cv)

a) TV = Constant

b) TVy = Constant

c) TVy-1 = Constant

d) T yV = Constant

41. The crystal having cell dimensions, a ¹ B ¹ c, a = b = g = 90ºhas structure

a) Tetragonal

b) Orthorhombic

c) Triclnic

d) Monoclinc

74. Which of the following possesses zero dipole moment?

a) NH3

b) CCl4

c) BF3

d) H2O

57. 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

58. Water becomes hard due to presence of soluble salt of ion

a) Al+3

b) Na

c) K

d) Ca2+

71. Pressure Volume relation for a mono-atomic gas undergoing adiabatic expansion:

a) PV1/3 = Constant

b) PV 2/3= Constant

c) PV 4/3= Constant

d) PV 5/3= Constant

72. At 0 K, fluids are assumed to have

a) minimum entropy

b) maximum entropy

c) zero entropy

d) a fixed value of entropy

76. Water has maximum density at

a) room temperature

b) 0°C

c) 4°C

d) 100°C

77. The water used in nuclear reactor is called

a) Hard water

b) Heavy water

c) Nuclear water

d) Critical water

78. The quantity remaining constant in isothermal expansion of an ideal gas:

a) Heat content

b) Internal energy

c) Pressure

d) Pressure and Temperature

83. Water gas is extremely poisonous due to presence of

a) N2

b) CO

c) H2

d) H2S

86. The quality of gasolene is expressed in terms of

a) Octane number

b) Cetane number

c) Gold number

d) Reynold’s number

87. 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

89. Which compound is used as rocket fuel?

a) Polybutadiene

b) N2H4

c) N3H

d) Both (A) and (B)

90. 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

91. The compound used in safety matches is

a) P4

b) PCl3

c) P2O5

d) P4S3

94. Permanent hardness of water is estimated by

a) Conductometne titration

b) lodometric titration

c) Acid-base titration

d) Complexometric EDTA titration

100. The gas used to extinguish fire:

a) CO₂

b) Ar

c) N2

d) CO

WBCS Main Question Paper – 2017

62. Crude petroleum is converted to number of hydrocarbon products by

(A) Fractional distillation

(B) Thermal cracking

(D) None of the above

65. The Redox indicator used in volumetric titration of

(A) Bromophynol Blue

(B) Methyl Orange

(D) Solochrome black-T

99. Gas released during Bhopal tragedy was :

(A) Sodium isothiocyanate

(B) Ethyl isothiocyanate

(D) Methyl isothiocyanate

101. Natural rubber is a polymer of

(A) Isoprene

(B) Styrene

(D) Butadiene

102. Tollens reagent is

(A) Alkaline mercuric chloride

(B) Alkaline potassium permanganate

(D) Ammonium citrate

103. Paraffin wax is

(A) Ester

(B) Alcohol

(D) saturated hydrocarbons

104. Which one of the following gas is used for artificial ripening of fruits ?

(A) Methane

(B) Acetylene

(D) Propane

105. Which one of the following materials does not show piezoelectric behavior ?

(A) Quartz

(B) Rochelle salt

(D) Barium titanate

106. The melting point of silica is

(A) 1710° C

(B) 2050°C

(D) 1810°C

107. The BET study is performed to measure

(A) particle size distribution

(B) specific surface area

(D) specific gravity

108. The potash feldspar is known as

(A) Orthoclase

(B) Albite

(D) Dickite

109. The acid employed for etching of glass is

(A) HCl

(B) HNO3

(D) HF

110. Which one of the following remains in solid state at room temperature ?

(melting point 113.7 °C)

(A) Cl2

(B) F2

(C) I2

(D) Br2

111. Mars gas contains

(CO2 – 95.32%, N2 – 2.6%, Ar – 1.9%)

(A) CO2

(B) CH4

(D) C2H6

112. Which one of following constitutes the common glass composition ?

(A) Sodium Silicate

(B) Calcium Silicate

(D) Lead Silicate

113. Stainless steel contains

(A) Fe + Cr + Ni

(B) Fe + Ni + Cu

(D) Fe + Co + Ni

114. Iron loses its magnetic property at

(1043 K / 7700 C)

(A) Melting point

(B) Curie point

(D) Boiling point

115. Bell metal is an alloy of

(A) Cu + Sn

(B) Cu + Zn

(D) Cu + Mn

116. Which element has the greatest ductility property ?

(most ductile metal – platinum, malleable metal – gold)

(A) Cu

(B) Ag

(D) Pt

117. Aluminum is extracted from bauxite by

(A) Bayer’s process

(B) Downs process

(D) Oswald process

118. The main radioactive element of pitch blende ore is

(A) Ra

(B) Th

(D) Po

119. The maximum consumption of refractories involves in

(A) Glass Industries

(B) Iron and Steel Plants

(D) Petroleum Industries

120. The most common element in the universe is

(A) Fe

(B) Ca

(D) Si(28%)

121. The process of zone refining is used for ultra-purification of

(A) Silicon

(B) Germanium

(D) All of the above

122. The base composition of whiteware body contains

(A) Clay, Quartz and Talc

(B) Quartz, Clay and Feldspar

(D) Clay, Gypsum and Feldsper

123. Which of the following metals do not form amalgam ?

(A) Iron

(B) Sodium

(D) Magnesium

124. Jam-jelly can be preserved by adding small percentage of

(A) HCHO

(B) EDTA

(D) CH3COOH

125. Reverse of swelling of gel is known as

(A) Syneresis

(B) Intestine

(D) Blood

151. Which one of the following is not peroxide ?

(A) BaO2

(B) Na2O2

(D) MnO2

152. Atomic packing density in FCC lattice is

(A) 0.47

(B) 0.68

(D) 1.0

155. 44 g of CO2 occupies how many litres of CO2 at STP ?

(A) 2.4 L

(B) 2.24 L

(D) 22.4 L

159. The contact angle of Hg on glass

(A) = 90°

(B) >90° (138°)

(D) None of the above

160. Forward chemical reactions happened only if

(G = Gibbs free energy)

(A) ΔG = 0

(B) ΔG > 0

(D) None of the above

163. Diamond has the Mohs’ scale hardness number of

(A) 5

(B) 7

(D) 9

164. Bakelite is the product of

(A) addition polymerization

(B) condensation polymerization

(D) None of the above

165. High polymerization of ethylene is done by using

(A) Zeolite catalyst

(B) V2O5 catalyst

(D) Pt-Mo catalyst

166. The isotope used for cancer therapy

(P-32, Na-24, Sr-89, Cs-137, Sm-153, Ir-192, Ac-225)

(A) I⁸⁰

(B) Co⁶⁰

(D) Ra²²³

167. Chemical used as insecticide is

(A) γ-BHC

(B) Methyl salicylate

(D) TNT

168. Number of unpaired electrons present in Cu2+.

(A) 3

(B) 5

(D) 1

169. Which one of these is not a transitional metal ?

(A) Ti

(B) Cr

(D) Zn

171. Diazo-coupling reaction between diazonium salt and naphthol produces

(A) Green dye

(B) Yellow dye

(D) Blue dye

172. Chemical formula of Grignard reagent is

(A) R-Mg-X

(B) R-Ca-X

(D) None of the above

176. The structure of α-alumina is

(A) Trigonal

(B) Orthorhombic

(D) Cubic

192. The isotope used as fuel in nuclear power plant is

(A) U235

(B) U238

(D) U239

178. Which of the following behaves as chemically most active non-metal ?

(A) F2 (Fluorine)

(B) He

(D) O2

179. A mixture of carbon monoxide and hydrogen is called

(A) Natural gas

(B) Water gas

(D) None of the above

180. Which fuel has the maximum calorific value ?

(Hydrogen highest – 150 KJ/g)

(A) Charcoal

(B) Kerosene

(D) LPG(50 KJ/g)

181. The hydrolysis of cane sugar is catalyzed by

(A) H+

(B) Enzymes

(D) All of the above

182. The catalyst used in the hydrogenation of oils is

(A) V2O5

(B) Ni

(D) Pt

183. Hydrochloric acid is also known is

(A) Chloric acid

(B) Muriatic acid

(D) Picric acid

184. Which one of the following element is essential for the construction of nuclear reactors ?

(A) Tungsten

(B) Platinum

(D) Zirconium

194. Martensitic steel has following crystal structure

(body-centered tetragonal crystal structure)

(A) BCC

(B) FCC

(D) HCP

WBCS Main Question Paper – 2016

28. 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

(D) becomes unsteady

47. In nuclear reaction, there is conservation of-

(A) energy only

(B) momentum only

(D) mass only

49. Particles which can be added to the nucleus of atom without changing its chemical properties are —

(A) electron

(B) protons

(D) α-particles

69. The number of unpaired electrons in Mn2+ is –

(A) 1

(B) 3

(D) 5

78. 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%

(D) 87.5%

91. Radioactive substance used in dating geological object is –

(A) C – 12

(B) C – 11

(D) None of the above

103. 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

(D) refracted by heavy atoms

118. Which one of the following is not radioactive ?

(A) Astatine

(B) Francium

(D) Zirconium

WBCS Main Question Paper – 2015

13. Which of the following is natural polymer ?

(condensation polymer)

(A) Terylene

(B) Orion

(D) Dacron

15. Marsh gas is

(CH4 + H2S + CO2)

(A) Methane

(B) Ethane

(D) None of the above

16. In the metallurgy of iron, the material obtained from bottom of the blast furnace is

(A) Slag

(B) Pig iron

(D) Wrought iron

17. The main ore of aluminum is

(A) Bauxite

(B) Alumina

(D) Cryolite

18. Which one is the unit of radio activity ?

(A) Curie

(B) Tasla

(D) Uranium

19. When a lead storage cell is charged

(A) Sulphuric Acid is consumed

(B) Sulphuric Acid is formed

(D) Lead is consumed

20. The temperature above which a real gas cannot be liquefied is known as

(A) Critical temperature

(B) Boyle temperature

(D) None of the above

22. Carnalite on electrolysis gives

A) Ca & Cl2

B) Na & CO2

C) Al & Cl2

D) Mg & Cl2

25. 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

(D) Butane, propane, ethane and methane

26. Which one of the following is known as RDX?

(Royal Demolition eXplosive)

(A) Cyanohydrin

(B) Dextran

(D) Cyclonite

29. Which one among the following is called Philosopher’s wool?

(A) Zinc Bromide

(B) Zinc Nitrate

(D) Zinc Chloride

31. Which one of the following does not contain silver?

(German silver – alloy of nickel, zinc & copper)

(A) Horn silver

(B) German silver

(D) Lunar Caustic

33. Which one of the following is also called a stranger gas?

(A) Argon

(B) Neon

(D) Nitrous oxide

34. Which one of the following is used as an explosive?

(A) Phosphorus trichloride

(B) Mercuric oxide

(D) Nitroglycerine

35. 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

(D) Carbon, Hydrogen, Potassium

42. D.D.T was invented by

(dichloro-diphenyl-trichloroethane)

(A) Paul Muller

(B) La Mark

(D) Darwin

91. The total of a given mass of a gas at a given temperature depends on

(A) Pressure

(B) Volume

(D) Temperature

95. In a nuclear reactor the chain reaction is controlled by introducing

(A) Iron rods

(B) Cadmium rods

(D) Platinum rods

99. When water is heated from 0°C to 10°C. Its Volume

(A) Increases

(B) Decreases

(D) First decreases then increases

185. Which of the following is a good nuclear fuel?

(U-233, U-235 & P-239)

(A) Uranium-238

(B) Neptunium-239

(D) Thorium-236

189. Most glass contain about 71 % by weight of

(A) Silicon dioxide

(B) Carbon dioxide

(D) Calcium carbonate

191. Gunpowder consists of a mixture of

(A) sand and TNT

(B) Sulphur, Sand and charcoal

(D) TNT and charcoal

WBCS Main Question Paper – 2014

6. The reaction that takes place inside the Sun to power it is

(A) Fission

(B) Fusion

(D) Decay

12. Naphthalene has the formula

(A) C6H6

(B) C10H8

(D) C12H12

15. The following substance is not an oxidizing agent

(A) Ozone

(B) Chloride

(D) Fluorine

20. The most electro-negative among the elements sodium, potassium, oxygen and fluorine is

(A) sodium

(B) potassium

(D) fluorine

21. The technique of barium X-ray utilizes the following property of barium sulphate

(A) It is opaque to X-rays

(B) It is radioactive

(D) It is easily absorbed by tissues

30. The basic molecule binds with other molecules to form a polymer is called

(A) macromolecule

(B) monomolecule

(D) monolith

36. 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

(D) 1/16

39. Epoxy resins are used as

(A) detergents

(B) insecticides

(D) moth repellents

86. Which of the following uranium isotopes is mostly used in nuclear reactors and nuclear weapons ?

(A) Uranium – 232

(B) Uranium – 234

(D) Uranium – 238

Chemistry – Science – WBCS Main Question Paper

wbcs main chemistry question paper

WBCS Main Question Paper – 2020

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