WBCS MAIN 2021 P-4 Science-Technology & EVS – Prosir – WBCS, WBPSC & West Bengal Competitive Exam Platform

WBCS MAIN 2021 P-4 Science-Technology & EVS MCQ

WBCS MAIN 2021 P-4 Science-Technology & EVS One Liner

Topic 1: Chemistry

1. Formula of baking powder is:

A. NaHCO3
B. Na2CO3·10H2O
C. Na2B4O7·10H2O
D. CaSO4·2H2O

Correct Answer: A. NaHCO3

2. Quinine is extracted from the plant of:

A. Poppy
B. Cinchona
C. Sandle wood
D. Palm

Correct Answer: B. Cinchona

3. The organic compound used as food preservative:

A. Methyl salicylate
B. Sodium benzoate
C. Sodium acetate
D. Sorbitol

Correct Answer: B. Sodium benzoate

4. The isotope used in cancer therapy:

A. Co58
B. C14
C. I131
D. Co60

Correct Answer: D. Co60

5. Carbon atom in benzene molecule is:

A. sp hybridised
B. sp² hybridised
C. sp³ hybridised
D. Not hybridised

Correct Answer: B. sp² hybridised

6. The carbolic acid is:

A. benzoic acid
B. phthalic acid
C. phenol
D. H2CO3

Correct Answer: C. phenol

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

A. Pyridine
B. Pyrole
C. Furan
D. Piperidine

Correct Answer: D. Piperidine

8. The oxide functioning as Piezoelectric substance:

A. Al2O3
B. ZrO2
C. TiO2
D. BaTiO3

Correct Answer: D. BaTiO3

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

A. Mica
B. Asbestos
C. Graphite
D. Silicones

Correct Answer: C. Graphite

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

A. PbCl2
B. Cu(OH)2
C. AgI
D. Al(OH)3

Correct Answer: C. AgI

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

A. substitution reaction
B. elimination
C. neutralisation reaction
D. disproportionation reaction

Correct Answer: D. disproportionation reaction

12. Graphite is used in nuclear reactor as:

A. Lubricant
B. Fuel rod
C. Control rod
D. Coating

Correct Answer: A. Lubricant

13. Black color of old oil painting can be cleaned by:

A. Cl2 water
B. H2O2
C. Nascent hydrogen
D. Oxalic acid

Correct Answer: B. H2O2

14. Which is the hardest material of the following?

A. Corundum
B. Diamond
C. SiC
D. B4C

Correct Answer: B. Diamond

15. NH3 gas is dried by using:

A. Conc. H2SO4
B. P2O5
C. Fused CaCl2
D. Quick Lime

Correct Answer: D. Quick Lime

16. In the contact process for the manufacture of H2SO4, V2O5 functions as:

A. oxidising agent
B. reducing agent
C. catalyst
D. neutralising agent

Correct Answer: C. catalyst

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

A. Concrete
B. RCC
C. Mortar
D. Monolith

Correct Answer: C. Mortar

18. Bronze is the alloy of:

A. Copper and Zinc
B. Copper and Tin
C. Copper and Nickel
D. Zinc and Tin

Correct Answer: B. Copper and Tin

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

A. Quenching
B. Annealing
C. Hardening
D. Cold working

Correct Answer: B. Annealing

20. The metal extracted from haematite using blast furnace:

A. Zn
B. Cu
C. Al
D. Fe

Correct Answer: D. Fe

21. The chemical bonding in diamond is:

A. Covalent
B. Ionic
C. Coordinate
D. Metallic

Correct Answer: A. Covalent

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

A. Phosphorous
B. Aluminum
C. Arsenic
D. None of the above

Correct Answer: B. Aluminum

23. Atomic defect responsible for reduction of bulk density of the material:

A. Schottky
B. Frankel
C. Interstitial
D. Electronic

Correct Answer: A. Schottky

24. The connecting material in solar panels is:

A. Si
B. Silver
C. Selenium
D. Cu

Correct Answer: C. Selenium

25. Which of the following is a artificial rubber?

A. Isoprene
B. Chloroprene
C. Neoprene
D. Teflon

Correct Answer: C. Neoprene

26. Phenol and Formaldehyde are used for the production of:

A. Caprolactum
B. Bakelite
C. PVC
D. Nylon 6

Correct Answer: B. Bakelite

27. 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.

Correct Answer: C. sum of protons and neutrons in the nucleus.

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

A. C2H2
B. H2
C. Cyanogen
D. Butane

Correct Answer: C. Cyanogen

29. Which material is used for production of automobile spring requiring high elastic property?

A. Copper
B. Steel
C. Brass
D. All of the above

Correct Answer: B. Steel

30. The crystal having cell dimensions, a ≠ b ≠ c, α = β = γ = 90° has structure:

A. Tetragonal
B. Orthorhombic
C. Triclinic
D. Monoclinic

Correct Answer: B. Orthorhombic

31. In medicine bottles containing capsules and tablets, a pouch of SiO2 gel is kept:

A. to kill bacteria
B. to absorb bacteria
C. to keep bottle warm
D. to absorb moisture

Correct Answer: D. to absorb moisture

32. 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

Correct Answer: D. 8 and 6

33. Water becomes hard due to presence of soluble salt of ion:

A. Al+3
B. Na+
C. K+
D. Ca+2

Correct Answer: D. Ca+2

34. Mention the main constituent of biogas and natural gas:

A. Ethane
B. Methane
C. Propane
D. Butane

Correct Answer: B. Methane

35. Pressure Volume relation for a monoatomic gas undergoing adiabatic expansion:

A. PV^γ = Constant
B. PV^γ-1 = Constant
C. TV^γ-1 = Constant
D. None of the above

Correct Answer: A. PV^γ = Constant

36. At 0 K, fluids are assumed to have:

A. minimum entropy
B. maximum entropy
C. zero entropy
D. a fixed value of entropy

Correct Answer: C. zero entropy

37. A Carnot engine operating between 27°C and 127°C has efficiency:

A. 21%
B. 22%
C. 24%
D. 25%

Correct Answer: D. 25%

38. Which of the following possesses zero dipole moment?

A. NH3
B. CCl4
C. BF3
D. H2O

Correct Answer: B. CCl4 (and C. BF3 – both correct, CCl4 more commonly cited)

39. The pressure gauge used for measuring very low vacuum of the order of 10⁻⁴ torr:

A. Bourdon pressure gauge
B. Hot filament ionisation gauge
C. McLeod gauge
D. inclined tube manometer

Correct Answer: C. McLeod gauge

40. The water used in nuclear reactor is called:

A. Hard water
B. Heavy water
C. Nuclear water
D. Critical water

Correct Answer: B. Heavy water

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

A. Heat content
B. Internal energy
C. Pressure
D. Pressure and Temperature

Correct Answer: B. Internal energy

42. The electrical resistivity of a semiconductor:

A. increases with temperature
B. decreases with temperature
C. does not change with temperature
D. increases at lower temperature but decreases at higher temperature

Correct Answer: B. decreases with temperature

43. The efficient utilisation of fly ash does not recommend for making:

A. portland fly ash cement.
B. fly ash based building bricks.
C. synthetic stone chips.
D. fillers in concrete.

Correct Answer: C. synthetic stone chips.

44. By which chemical reaction, biodiesel is being prepared?

A. Fermentation
B. Combustion
C. Polymerisation
D. Trans esterification

Correct Answer: D. Trans esterification

45. Water gas is extremely poisonous due to presence of:

A. N2
B. CO
C. H2
D. H2S

Correct Answer: B. CO

46. The quality of gasoline is expressed in terms of:

A. Octane number
B. Cetane number
C. Gold number
D. Reynold’s number

Correct Answer: A. Octane number

47. Which of the following is a complex salt?

A. Al(NO3)3·9H2O
B. K4[Fe(CN)6]
C. K2SO4·Cr(SO4)3·24H2O
D. Ca(OCl)Cl

Correct Answer: B. K4[Fe(CN)6]

48. Which compound is used as rocket fuel?

A. Polybutadiene
B. N2H4
C. N2H
D. Both (A) and (B)

Correct Answer: D. Both (A) and (B)

49. 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

Correct Answer: C. plastic sulphur

50. The compound used in safety matches is:

A. P4
B. PCl3
C. P2O5
D. P4S3

Correct Answer: D. P4S3

51. Permanent hardness of water is estimated by:

A. Conductometric titration
B. Iodometric titration
C. Acid-base titration
D. Complexometric EDTA titration

Correct Answer: D. Complexometric EDTA titration

52. The photochemical smog is generated by:

A. HCHO
B. PAN (Peroxy acetyl nitrate)
C. Acrolin
D. Moisture

Correct Answer: B. PAN (Peroxy acetyl nitrate)

53. Chlorophyll contains:

A. Zinc
B. Iron
C. Magnesium
D. Cobalt

Correct Answer: C. Magnesium

54. The gas used to extinguish fire:

A. CO2
B. Ar
C. N2
D. CO

Correct Answer: A. CO2

Topic 2: Physics

55. If the current passing through a resistance increases by two times, the heat generated will increase by:

A. 2 times
B. 4 times
C. 6 times
D. 8 times

Correct Answer: B. 4 times

56. Largest amount of energy, the earth receiving from the sun is in the form of:

A. Infrared and heat energy
B. γ-rays
C. UV-rays
D. X-rays

Correct Answer: A. Infrared and heat energy

57. Electric power has the unit of:

A. Volt
B. Watt
C. Coulomb
D. Ampere

Correct Answer: B. Watt

58. Sound wave having frequency more than 20,000 Hertz is known as:

A. Ultrasonic
B. Supersonic
C. Microwave
D. Seismic

Correct Answer: A. Ultrasonic

59. Spin of ‘Boson’ particle is equal to:

A. positive integer
B. negative integer
C. positive integral multiple of 1/2
D. any fraction

Correct Answer: A. positive integer

60. 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.

Correct Answer: B. chemical changes.

61. Walk on a smooth floor causes fatal fall because:

A. grip of legs with the floorsurface minimises.
B. frictional force nil.
C. centre of gravity of body changes.
D. increase of forwarding forces.

Correct Answer: A. grip of legs with the floorsurface minimises.

62. Temperature (K) and volume (V) relationship of a gas undergoing adiabatic expansion (γ = Cp/Cv):

A. TV = Constant
B. TV^γ = Constant
C. TV^(γ-1) = Constant
D. TV^γ-1 = Constant

Correct Answer: C. TV^(γ-1) = Constant

63. IC in computer stands for:

A. Internal Circuits
B. Integrated Circuits
C. Integrated Current
D. Integrated Charge

Correct Answer: B. Integrated Circuits

64. Quality of a musical note depends on:

A. fundamental frequency
B. harmonics
C. amplitude of the wave
D. velocity of sound

Correct Answer: B. harmonics

65. Wavelength of visible light lies in between:

A. 400 to 800 nm
B. 500 to 1000 nm
C. 300 to 600 nm
D. 200 to 400 nm

Correct Answer: A. 400 to 800 nm

66. The device that converts AC to DC is called:

A. Transformer
B. Rectifier
C. Induction motor
D. Dynamo

Correct Answer: B. Rectifier

67. Water has maximum density at:

A. Room temperature
B. 0°C
C. 4°C
D. 100°C

Correct Answer: C. 4°C

68. The resistance of an ideal ammeter is:

A. zero
B. small
C. high
D. very high

Correct Answer: A. zero

69. Solar spectrum is the example of:

A. continuous emission spectrum.
B. band absorption spectrum.
C. line absorption spectrum.
D. continuous absorption spectrum.

Correct Answer: C. line absorption spectrum.

Topic 3: Biology

70. Carbohydrate stored in the body as:

A. glucose
B. starch
C. glycogen
D. sucrose

Correct Answer: C. glycogen

71. The human eye forms the image of an object at its:

A. retina
B. cornea
C. iris
D. None of the above

Correct Answer: A. retina

72. The normal blood pressure of human beings should remain in the range of:

A. 120/80 mm
B. 110/70 mm
C. 140/80 mm
D. 110/60 mm

Correct Answer: A. 120/80 mm

73. Universal recipient blood group is:

A. AB
B. O
C. B
D. A

Correct Answer: A. AB

74. Which one of the following is considered as good cholesterol?

A. VLDL
B. LDL
C. HDL
D. Triglycerides

Correct Answer: C. HDL

75. Goitre is caused by the deficiency of:

A. Vitamin A
B. Vitamin D
C. Iodine
D. Calcium

Correct Answer: C. Iodine

76. Plant absorbs dissolved nitrates from soil and converts them into:

A. free N2
B. urea
C. ammonia
D. proteins

Correct Answer: C. ammonia

77. The heart rate of adult persons should remain in the range of:

A. 50-60 times per minute
B. 70-80 times per minute
C. 40-50 times per minute
D. 90-100 times per minute

Correct Answer: B. 70-80 times per minute

78. The method by which desired characters of two plants can be combined:

A. Cutting
B. Layering
C. Budding
D. Grafting

Correct Answer: D. Grafting

79. Which organ is not controlled by autonomous nervous system?

A. Heart
B. Uterus
C. Glands
D. Eyes

Correct Answer: D. Eyes

80. Blood is filtered in the body through:

A. Liver
B. Kidney
C. Lungs
D. None of the above

Correct Answer: B. Kidney

Topic 4: Environmental Science

81. BOD value will be maximum in:

A. waste water
B. river water
C. rain water
D. sewage water

Correct Answer: D. sewage water

82. During Bhopal gas tragedy, the harmful gas evolved was:

A. Phosgene
B. Ammonia
C. Carbyl amine
D. Methyl isocyanate

Correct Answer: D. Methyl isocyanate

83. Which ray strikes the earth due to depletion of O3 layer?

A. Infrared
B. Microwave
C. Visible
D. Ultraviolet

Correct Answer: D. Ultraviolet

84. Which one of the following is responsible for depletion of O3 layer?

A. CO2
B. Chlorofluorocarbon
C. CH4
D. None of the above

Correct Answer: B. Chlorofluorocarbon

85. Which one of the following gases reacts with haemoglobin and produces toxic effect?

A. CO2
B. SO2
C. NO2
D. CO

Correct Answer: D. CO

86. Which one of the following statements is false?

A. River pollution is due to industrial and domestic sewage discharge.
B. Surface water contains a lot of organic matters and nutrients.
C. Oil slick in sea increases dissolved oxygen content.
D. Oil spill in sea causes heavy damage to fishery.

Correct Answer: C. Oil slick in sea increases dissolved oxygen content.

87. The largest reservoir of nitrogen gas in environment is:

A. Air
B. Earth’s Crust
C. Ocean
D. Plants and animals

Correct Answer: A. Air

88. The aim of rain water harvesting is to:

A. recharge groundwater
B. avoid floods
C. control soil erosion
D. conservation of freshwater

Correct Answer: A. recharge groundwater

89. In which ecosystem, grassland is included?

A. Marine
B. Freshwater
C. Terrestrial
D. Artificial

Correct Answer: C. Terrestrial

90. Which part of atmosphere is richest in O3 gas?

A. Stratosphere
B. Ionosphere
C. Exosphere
D. Magnetosphere

Correct Answer: A. Stratosphere

91. …………… assists in environmental protection.

A. Urbanisation
B. Nuclear explosion
C. Industrialisation
D. Plantation and Forestation

Correct Answer: D. Plantation and Forestation

92. Hydrosphere does not cover:

A. Oceans
B. Rivers
C. Glaciers
D. Rocks

Correct Answer: D. Rocks

93. World Environment Day is observed on:

A. 14th November
B. 27th February
C. 5th June
D. 5th September

Correct Answer: C. 5th June

94. Soil is rarely contaminated due to:

A. Acid rain
B. Chemical fertilizers
C. Pesticides
D. Mineralisation

Correct Answer: D. Mineralisation

95. Which one of the following is not included within the atmosphere?

A. Troposphere
B. Stratosphere
C. Lithosphere
D. Ozonosphere

Correct Answer: C. Lithosphere

96. Which of the following is a biodegradable pollutant?

A. Dye effluent
B. Bleaching effluent
C. Sewage
D. Heavy metals

Correct Answer: C. Sewage

97. The first step of sewage treatment:

A. Precipitation
B. Chlorination
C. Airation
D. Sedimentation

Correct Answer: D. Sedimentation

Topic 5: Current Affairs & General Knowledge

98. Which of the following award is being given in the field of Science and Technology?

A. Arjun Award
B. Bharat Ratna
C. Padma Bhusan
D. Shanti Swarup Bhatnagar Award

Correct Answer: D. Shanti Swarup Bhatnagar Award

TOPIC-WISE SUMMARY

Topic No.	Topic Name	Question Numbers
1	Chemistry	1-54
2	Physics	55-69
3	Biology	70-80
4	Environmental Science	81-97
5	Current Affairs & General Knowledge	98