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Multiple choice question for engineering

Set 1

1. A fuel cell is used to convert chemical energy into
a) Mechanical energy
b) Solar energy
c) Electrical energy
d) Potential energy

View Answer

Answer: c [Reason:] A fuel cell is used to convert chemical energy into electrical energy through a chemical reaction of positively charged hydrogen ions with oxygen or another oxidizing agent.

2. Select the incorrect statement from the following option.
a) Fuel cells have high efficiency
b) The emission levels of fuel cells are far below the permissible limits
c) Fuel cells are modular
d) The noise levels of fuel cells are high

View Answer

Answer: d [Reason:] The noise levels of fuel cells are low. They have high efficiency and are modular but the emission levels of fuel cells are far below the permissible limits.

3. ______________ and suitable catalyst are required to promote high rate of electrode processes.
a) Lower temperature
b) Higher temperature
c) Moderate temperature
d) Very low temperature

View Answer

Answer: b [Reason:] Higher temperature and suitable catalyst are required to promote high rate of electrode processes. The reaction at the anode produces electricity and water as by-products. The catalyst lowers the activation energy required, allowing the reaction to proceed more quickly or at a lower temperature.

4. State true or false. Fuel cells are free from vibrations, heat transfer and thermal pollution.
a) True
b) False

View Answer

Answer: a [Reason:] Fuel cells are free from vibrations, heat transfer and thermal pollution. The first commercial use of fuel cells came more than a century later in NASA space programs to generate power for satellites and space capsules.

5. A stable interface between solid _________ liquid ____________ and gaseous ___________ promotes high rate of electrode processes.
a) Fuel, electrolyte, electrode
b) Electrode, fuel, electrolyte
c) Electrode, electrolyte, fuel
d) Fuel, electrode, electrolyte

View Answer

Answer: c [Reason:] A stable interface between solid electrode, liquid electrolyte and gaseous fuel promotes high rate of electrode processes. Electrodes are always solid and electrolyte is always in liquid phase.

6. Which of the following is not an example of fuel cell?
a) Hydrogen-oxygen cell
b) Methyl-oxygen-alcohol cell
c) Propane-oxygen cell
d) Hexanone-oxygen cell

View Answer

Answer: d [Reason:] Hydrogen-oxygen cell, methyl-oxygen-alcohol cell and propane-oxygen cell are some of the examples of fuel cells. Hexanone-oxygen cell is not an example of fuel cell.

7. The electrolytic solution used in hydrogen-oxygen fuel cell is
a) 75% KOH solution
b) 25% KOH solution
c) 75% NaOH solution
d) 25% NaOH solution

View Answer

Answer: b [Reason:] The electrolytic solution used in hydrogen-oxygen fuel cell is 25% KOH solution by volume.

8. The standard emf of the hydrogen-oxygen fuel cell is
a) 1.23 V
b) 2.54 V
c) 3.96 V
d) 0.58 V

View Answer

Answer: a [Reason:] The standard emf of the hydrogen-oxygen fuel cell is 1.23 V. This type of cell operates efficiently in the temperature range 343 K to 413 K.

9. The residual product discharged by the hydrogen-oxygen cell is
a) Hydrogen peroxide
b) Alcohol
c) Water
d) Potassium permanganate

View Answer

Answer: c [Reason:] The residual product discharged by the hydrogen-oxygen cell is water. It is formed by the oxidation reaction taking place at electrodes and combining the hydrogen and oxygen molecules.

10. State true or false. Hydrogen-oxygen fuel cell can produce drinking water of potable quality.
a) True
b) False

View Answer

Answer: a [Reason:] Hydrogen-oxygen fuel cell can produce drinking water of potable quality because the residual product discharged by the hydrogen-oxygen cell is water which is in its pure form.

Set 2

1. Select the incorrect statement from the following option.
a) Nitonol is a non-magnetic material
b) It has a shape memory strain of about 8.5%
c) It has lower ductility than other shape memory alloys like Au-Cd
d) It possess excellent corrosion resistant

View Answer

Answer: c [Reason:] Nitinol has higher ductility than other shape memory alloys like Au-Cd and can freely revert back to its original shape. All the other options are correct. It is a non-magnetic material and possess excellent corrosion resistant.

2. The materials which offer no resistance to the passage of electricity are
a) Superconductors
b) Semiconductors
c) Optical fibre
d) Smart material

View Answer

Answer: a [Reason:] Superconductors offer no resistance to the passage of electricity. Semi-conductor is a substance, usually a solid chemical element or compound, that can conduct electricity under some conditions but not others, making it a good medium for the control of electrical current.

3. The critical temperature for the cuprate La2CuO4 is
a) 40 K
b) 90 K
c) 125 K
d) 35 K

View Answer

Answer: d [Reason:] The critical temperature for the cuprate La2CuO4 is 35 K. Cuprate loosely refers to a material that can be viewed as containing copper anions.

4. Identify the class of the superconductor to which TiO and NbO belongs.
a) Simple compounds
b) Nonstoichiometric crystals having defects
c) Charge-transfer compounds
d) Molecular crystals

View Answer

Answer: b [Reason:] TiO and NbO are the examples of non-stoichiometric crystals having defects class of superconductors.

5. The dielectric material that shows spontaneous and reversible dielectric polarisation are
a) Piezoelectrics
b) Pyroelectrics
c) Ferroelectrics
d) None of the mentioned

View Answer

Answer: c [Reason:] Piezoelctrics are those dielectric materials in which pressure can produce an electrical response and electrical forces produce a mechanical response. Pyroelectrics are those dielectric in which polarisation changes with temperature. Ferroelectrics are those dielectric material that shows spontaneous and reversible dielectric polarisation.

6. What is the principle on which an optical fibre works?
a) Total internal reflection
b) Farraday’s law of induction
c) Doppler Effect
d) Hooke’s law

View Answer

Answer: a [Reason:] Due to total internal reflection, light can be transmitted over many kilometers without any appreciable decrease in the intensity by optical fibres.

7. Optical fibre can be safely used for signal transmission near the nuclear installation because
a) There is no leakage of signals
b) Plastic cladded silica fibres are resistant to nuclear radiations
c) Plastic cladded silica fibres are not resistant to nuclear radiations
d) There is no electromagnetic interference

View Answer

Answer: b [Reason:] Optical fibre can be safely used for signal transmission near the nuclear installation because the plastic cladded silica fibres are resistant to nuclear radiations. Due to total internal reflection, light can be transmitted over many kilometers without any appreciable decrease in the intensity by optical fibres.

8. The correct sequence for the procedure adopted for making a pure elemental semiconductor consist of
a) Preparation of ultrapure Si or Ge>> Doping>> Preparation of single crystals of Si or Ge
b) Doping>> Preparation of ultrapure Si or Ge>> Preparation of single crystals of Si or Ge
c) Preparation of ultrapure Si or Ge>> Preparation of single crystals of Si or Ge>> Doping
d) Preparation of single crystals of Si or Ge>> Preparation of ultrapure Si or Ge>> Doping

View Answer

Answer: c [Reason:] The correct sequence for the procedure adopted for making a pure elemental semiconductor consist of: Preparation of ultrapure Si or Ge>> Preparation of single crystals of Si or Ge>> Doping

9. Which of the following is not an application of a transistor?
a) Tunnel diodes
b) Thermistors
c) Amplifiers
d) None of the mentioned

View Answer

Answer: d [Reason:] All the mentioned options are the applications of transistor. A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. It is used for tunnel diodes, thermistors and amplifiers.

10. The amplification factor for transistor when used as an amplifier will be
a) 25
b) 50
c) 75
d) 100

View Answer

Answer: b [Reason:] The amplification factor for transistor when used as an amplifier will be 50. Modern transistor audio amplifiers of up to a few hundred watts are common and relatively inexpensive.

Set 3

1. Galvanic series gives real and useful information regarding the
a) Electrical conductivity of metals and alloys
b) Thermal conductivity of metals and alloys
c) Corrosion behaviour of metals and alloys
d) Oxidation power of metals and alloys

View Answer

Answer: c [Reason:] Galvanic series gives real and useful information regarding the corrosion behaviour of metals and alloys in a given environment, i.e. which metal will corrode at fastre rate and which will not corrode at all.

2. Which of the following is the most noble metal?
a) Gold
b) Graphite
c) Titanium
d) Platinum

View Answer

Answer: d [Reason:] Platinum is the most noble metal present at the protected end of galvanic series. It does not corrode easily.

3. Which of the following is the least noble metal?
a) Magnesium
b) Brass
c) Aluminium
d) Nickel

View Answer

Answer: a [Reason:] Magnesium is the least noble metal present at the corroded end of galvanic series. It corrodes very easily and at very fast rate.

4. Arrange the following in the ascending order of their degree of corrosion.
a) Zinc >> Magnesium >> Copper >> Lead >> Aluminium
b) Copper >> Lead >> Aluminium >> Zinc >> Magnesium
c) Zinc >> Magnesium >> Lead >> Copper >> Aluminium
d) Copper >> Aluminium >> Zinc >> Lead >> Magnesium

View Answer

Answer: b [Reason:] The correct order is Copper >> Lead >> Aluminium >> Zinc >> Magnesium. Magnesium is the most active towards corrosion and copper is the least active towards corrosion among the given elements.

5. As the distance between two metals increases in galvanic series, the degree of corrosion
a) Increases
b) Decreases
c) Remains same
d) First increases then decreases

View Answer

Answer: a [Reason:] As the distance between two metals increases in galvanic series, the degree of corrosion increases. elements are arranged in the decreasing order of corrosion in the galvanic series.

6. Which of the following metals are protected metals?
a) Present at the top
b) Present at the middle
c) Present at the bottom
d) Both present at the top and the bottom

View Answer

Answer: c [Reason:] The metals which are present at the bottom of the galvanic series are the protected metals. These are the least active towards corrosion and hence also called noble or protected metals.

7. Which electrode is used for measuring electrode potential as standard electrode in galvanic series?
a) Hydrogen electrode
b) Calomel electrode
c) Oxygen electrode
d) Nitrogen electrode

View Answer

Answer: b [Reason:] Calomel electrode is used for measuring electrode potential as standard electrode in galvanic series. it gives the value of electrode potential of different electrodes.

8. State true or false. The galvanic series predicts the relative displacement tendencies of metals and non-metals in electrolytes containing particular concentration of salts.
a) True
b) False

View Answer

Answer: b [Reason:] The galvanic series predicts the corrosion tendencies of metals and non-metals in actual environment. It has been drawn up for metals and alloys in sea water, which shows their relative nobility.

9. The phenomenon by which a metal or alloy show high corrosion resistance due to formation of highly protective film is called
a) Electrolysis
b) Electrodialysis
c) Galvanisation
d) Passivation

View Answer

Answer: d [Reason:] The phenomenon by which a metal or alloy show high corrosion resistance due to formation of highly protective film is called passivation. Passivation is the use of a light coat of a protective material, such as metal oxide, to create a shell against corrosion.

10. The thickness of the protective film in passivation is about
a) 1 mm
b) 0.02 mm
c) 0.0004 mm
d) 0.004 mm

View Answer

Answer: c [Reason:] The thickness of the protective film in passivation is about 0.0004 mm. Passivation is the use of a light coat of a protective material, such as metal oxide, to create a shell against corrosion.

Set 4

1. Hardness of water is due to the presence of salts of
a) Potassium
b) Chlorine
c) Magnesium
d) Boron

View Answer

Answer: c [Reason:] Hardness of water is due to the presence of salts of calcium and magnesium. Hard drinking water may have moderate health benefits, but can pose serious problems in industrial settings, where water hardness is monitored to avoid costly breakdowns in boilers, cooling towers, and other equipment that handles water.

2. Select the incorrect statement from the following option.
a) Water which does not form lather with soap and forms white scum is called hard water
b) Hard water contains dissolved calcium and magnesium salts in it
c) In hard water, cleansing quality of soap is depressed
d) Due to the presence of dissolved hardness-producing salts, the boiling point of water is depressed

View Answer

Answer: d [Reason:] Due to the presence of dissolved hardness-producing salts, the boiling point of water is elevated. Elevation in boiling point is one of the most important colligative property. All the other options are correct.

3. Select the incorrect statement from the following option.
a) Permanent hardness is due to dissolved chlorides and sulphates of calcium and magnesium
b) It can be removed by mere boiling of water
c) It is also known as non-alkaline hardness
d) The difference between the total hardness and the alkaline hardness gives the non-alkaline hardness

View Answer

Answer: b [Reason:] Unlike temporary hardness, permanent hardness is not destroyed on boiling. Varoius methods are adopted for the removal of permanent hardness like zeolites, lime-soda process etc. All the other options are correct.

4. State true or false. Alkaline hardness is due to the presence of bicarbonate, carbonate and hydroxides of the hardness-producing metal ions.
a) True
b) False

View Answer

Answer: a [Reason:] Alkaline hardness is due to the presence of bicarbonate, carbonate and hydroxides of the hardness-producing metal ions. This is also called carbonate hardness. It is temporary and can be removed easily by boiling.

5. Select the incorrect statement from the following option.
a) The taste of hard water is better than soft water
b) The dissolved calcium in hard water can help to produce strong teeth
c) Hard water coats the lead piping with a layer of insoluble calcium carbonate which prevents poisonous lead dissolving in water
d) Boiler feed water should also be hard in nature

View Answer

Answer: d [Reason:] Boiler feed water should be free from hardness otherwise explosion may occur. All the other options are correct. The taste of hard water is better than soft water and dissolved calcium in hard water can help to produce strong teeth. Hard water coats the lead piping with a layer of insoluble calcium carbonate which prevents poisonous lead dissolving in water.

6. Hardness of water is conventionally expressed in terms of equivalent amount of
a) H2CO3
b) MgCO3
c) CaCO3
d) Na2 CO3

View Answer

Answer: c [Reason:] Hardness of water is conventionally expressed in terms of equivalent amount of CaCO3. The total water hardness is the sum of the molar concentrations of Ca2+ and Mg2+, in mol/L or mmol/L units.

7. The chemical equivalent of MgSO4 salt is
a) 60
b) 47.5
c) 82
d) 68

View Answer

Answer: a [Reason:] The molar mass of MgSO4 is 120 and its n-factor is 2. So, chemical equivalent = Molar mass/ n-factor = 60.

8. Which of the following is not a unit of hardness?
a) Parts per million
b) Degree centigrade
c) Degree clarke
d) Degree French

View Answer

Answer: b [Reason:] Degree centigrade is not a unit of hardness. Degree centigrade is the unit of temperature. The unit for hardness is ppm (parts per million), degree clarke and degree french. All these three units are inter-related.

9. 1 degree Clarke = 1 part of CaCO3 per _____________ parts of water.
a) 10,000
b) 30,000
c) 50,000
d) 70,000

View Answer

Answer: d [Reason:] 1 degree Clarke = 1 part of CaCO3 per 70,000 parts of water. It is calculated mathematically.

10. 1 ppm =
a) 0.07 0Fr
b) 0.70Fr
c) 0.10Fr
d) 0.010Fr

View Answer

Answer: c [Reason:] 1 ppm = 0.10Fr.It is calculated mathematically.

11. How many grams of MgCO3 dissolved per litre gives 84 ppm hardness?
a) 70.56 mg/L
b) 48.23 mg/L
c) 81.49mg/L
d) 66.12 mg/L

View Answer

Answer: a. [Reason:] 70.56 mg/L of MgCO3 dissolved per litre gives 84 ppm hardness.

12. State true or false. EDTA method for hardness determination is less accurate and inconvenient procedure.
a) True
b) False

View Answer

Answer: b [Reason:] EDTA method for hardness determination is more accurate, convenient and rapid procedure. Ethylene diaminetetraacetic acid (EDTA), is an amino poly-carboxylic acid and a colorless, water-soluble solid.

Set 5

1. Which of the following molecule is not homonuclear?
a) H2
b) N2
c) NO
d) O2

View Answer

Answer: c [Reason:] NO is Heteronuclear diatomic molecule in which atomic number of nitrogen is 7 and that of oxygen is 8 i.e., total number of electrons = 15.

2. Bond order of NO+ molecule is
a) 2
b) 3
c) 2.5
d) 4

View Answer

Answer: b [Reason:] Bond order = (10-4)/ 2 = 3

3. Which of the following molecule is least stable?
a) NO+
b) N2
c) NO
d) O2

View Answer

Answer: c [Reason:] In NO molecule there is a significant difference of about 250 kJ/mol in the energy of atomic orbitals involved.

4. The molecular orbital electronic configuration of HF molecule is
a) 1s2 2s2 σspx2 [2py2 2pz2] σspx*
b) 1s2 2s2 σspx2 [2px2 2py2] σspx*
c) 1s2 2s2 σspx2 [2px2 2pz2] σspx*
d) 1s2 2s2 σspx2 [2px4] σspx*

View Answer

Answer: a [Reason:] HF molecule has 10 electrons and its electronic configuration is 1s2 2s2 σspx2 [2py2 2pz2] σspx*.

5. From the following options, choose the heteronuclear diatomic molecules which are paramagnetic in nature?
a) HF and NO
b) HF and O2
c) NO and O2
d) Only NO

View Answer

Answer: d [Reason:] HF is diamagnetic in nature and O2 is homonuclear molecule. So, only NO is heteronuclear diatomic molecule which is paramagnetic in nature.

6. Calculate the number of σ and π bonds in cyclohexadiene. (C6H8)
a) σ bond = 2 π bond = 14
b) σ bond = 14 π bond = 2
c) σ bond = 12 π bond = 2
d) σ bond = 12 π bond = 4

View Answer

Answer: b [Reason:] Cyclohexadiene molecule has two double bonds( hence two π-bonds) and one ring.

7. The combination of H (1s1) and F (2px1) gives
a) Bonding orbital
b) Antibonding orbital
c) Both bonding and antibonding orbital
d) None of the mentioned

View Answer

Answer: c [Reason:] The combination of H (1s1) and F (2px1) gives both bonding (σspx) and antibonding (σspx*) orbitals.

8. Choose the incorrect option from the following.
a) Valence bond theory does not explain the paramagnetic nature of O2
b) Molecular orbital theory explains the extra stability of O2+ cation over O2
c) Valence bond theory explains the ionization or gain of electrons, giving O2+ and O2 ions, if O2 has the stable octet
d) Resonance has no role in Molecular orbital theory

View Answer

Answer: c [Reason:] Valence bond theory does not explain the ionization or gain of electrons, giving O2+ and O2 ions, if O2 has the stable octet.

9. Which of the following molecules have bond order equal to 1?
a) NO, HF, HCl, Li2, CO
b) H2, Li2, B2, HF, HCl
c) Li2, B2, CO, NO,He2+
d) B2, CO, He2+, NO, HF

View Answer

Answer: b [Reason:] He2+ = 0.5, H2, Li2, B2, HF, HCl = 1, NO = 2.5, CO = 3

10. The interaction between pair of orbitals of the same type is
a) Attractive
b) Repulsive
c) There is no interaction
d) None of the mentioned

View Answer

Answer: b [Reason:] The interaction between pair of orbitals of the same type is repulsive like between σ2s and σ2p orbitals.

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