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Unit 6: Energy sciences - Practice Quiz

CHE124 — Engineering Chemistry 60 Questions
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1 The calorific value of a fuel is defined as the amount of heat produced by the complete combustion of a:

Calorific value of fuels Easy
A. Unit mass of the fuel
B. Unit mole of oxygen
C. Unit area of the fuel surface
D. Unit volume of air

2 Which of the following is the standard SI unit for expressing the calorific value of a solid fuel?

Calorific value of fuels Easy
A.
B.
C.
D.

3 The difference between Gross Calorific Value (GCV) and Net Calorific Value (NCV) arises mainly due to the:

Calorific value of fuels Easy
A. Latent heat of condensation of water vapour
B. Amount of ash formed
C. Presence of nitrogen gas
D. Volume of the combustion chamber

4 Which instrument is commonly used in the laboratory to determine the calorific value of solid and liquid fuels?

determination of calorific value Easy
A. Ostwald viscometer
B. Bourdon gauge
C. Bomb calorimeter
D. Bunsen burner

5 Which calorimeter is typically used to determine the calorific value of gaseous fuels?

determination of calorific value Easy
A. Bomb calorimeter
B. Coffee cup calorimeter
C. Junkers calorimeter
D. Differential scanning calorimeter

6 The proximate analysis of coal determines moisture, volatile matter, ash and:

analysis of coal Easy
A. Hydrogen content
B. Sulphur content
C. Nitrogen content
D. Fixed carbon

7 Which type of coal analysis determines the percentage of elements such as carbon, hydrogen, nitrogen, sulphur and oxygen present in the coal sample by direct chemical estimation?

analysis of coal Easy
A. Proximate analysis
B. Thermal analysis
C. Gravimetric titration
D. Ultimate analysis

8 Which of the following is an example of a naturally occurring solid fuel?

energy sciences: fuels and its types Easy
A. Natural gas
B. Petrol
C. Diesel
D. Coal

9 Fuels are broadly classified based on their occurrence into primary fuels and:

energy sciences: fuels and its types Easy
A. Liquid fuels
B. Renewable fuels
C. Nuclear fuels
D. Secondary (derived) fuels

10 A key characteristic of a primary cell is that it:

Primary cells Easy
A. Uses only liquid fuel as reactant
B. Can be recharged many times
C. Cannot be recharged once discharged
D. Produces electricity from sunlight

11 Which of the following is a common example of a primary cell?

Primary cells Easy
A. Li-ion battery
B. Ni-Cd battery
C. Lead-acid battery
D. Dry cell (Leclanché cell)

12 Secondary batteries differ from primary cells because they are:

Secondary batteries Easy
A. Used only once and discarded
B. Powered by nuclear reactions
C. Unable to store any charge
D. Rechargeable and reusable

13 In a lead storage battery, the electrolyte used is:

Lead storage battery Easy
A. Hydrochloric acid
B. Potassium hydroxide
C. Dilute sulphuric acid
D. Sodium chloride solution

14 Lead storage batteries are most commonly used in:

Lead storage battery Easy
A. Wristwatches
B. Automobiles
C. Hearing aids
D. TV remote controls

15 In a lithium-ion battery, charge is carried between the electrodes by the movement of:

Li-ion battery Easy
A. Lithium ions ()
B. Electrons through the electrolyte
C. Chloride ions
D. Hydrogen ions

16 Which of the following devices most commonly uses a Li-ion battery?

Li-ion battery Easy
A. Wall clock powered by a single cell
B. Car ignition starter of a truck
C. Emergency torch with a zinc-carbon cell
D. Smartphone

17 The two active electrode materials used in a Ni-Cd battery are nickel oxide-hydroxide and:

Ni-Cd Easy
A. Zinc
B. Cadmium
C. Lithium
D. Lead

18 In a Ni-metal hydride (Ni-MH) battery, the negative electrode is made of:

Ni-metal hydride battery Easy
A. Pure cadmium metal
B. Graphite rod
C. Lead dioxide
D. A hydrogen-absorbing metal alloy

19 A fuel cell converts the chemical energy of a fuel directly into:

Fuel cells- principles, applications, advantages/disadvantages Easy
A. Sound energy
B. Nuclear energy
C. Mechanical energy
D. Electrical energy

20 Hydrogen is considered a clean energy carrier mainly because its combustion with oxygen produces:

hydrogen energy (production, storage, safety aspects) and significance as a clean and sustainable energy carrier Easy
A. Sulphur dioxide
B. Water
C. Nitrogen oxides
D. Carbon dioxide

21 In a Bomb calorimeter experiment, g of fuel raised the temperature of g of water by . Taking water equivalent of the apparatus as negligible and specific heat of water as , the gross calorific value of the fuel is approximately:

determination of calorific value Medium
A.
B.
C.
D.

22 Why is the Net (Lower) Calorific Value always less than the Gross (Higher) Calorific Value of a fuel?

determination of calorific value Medium
A. NCV is measured at higher pressure than GCV
B. GCV ignores the sulphur content of the fuel
C. NCV includes the heat of formation of ash
D. Latent heat of condensation of water vapour is not recovered in NCV

23 In the proximate analysis of coal, which property is determined by heating the coal sample in the absence of air at about after moisture removal?

analysis of coal Medium
A. Volatile matter
B. Sulphur content
C. Ash content
D. Fixed carbon

24 A coal sample has moisture, volatile matter, and ash by proximate analysis. What is the percentage of fixed carbon?

analysis of coal Medium
A.
B.
C.
D.

25 Which analysis of coal directly determines the percentage of C, H, N, S and O present in the coal?

analysis of coal Medium
A. Thermogravimetric analysis
B. Proximate analysis
C. Bomb calorimetry
D. Ultimate analysis

26 During the discharge of a Ni-Cd battery, what happens at the negative electrode?

Ni-Cd Medium
A. is reduced to
B. Cd is reduced to metallic Cd
C. is oxidized to
D. Cd is oxidized to

27 A major advantage of Ni-MH batteries over Ni-Cd batteries is that they:

Ni-metal hydride battery Medium
A. Use a non-aqueous organic electrolyte
B. Are completely free from the memory effect
C. Deliver a much higher cell voltage per cell
D. Avoid toxic cadmium and offer higher energy density

28 In a Li-ion battery, which process occurs at the graphite anode during charging?

Li-ion battery Medium
A. Oxidation of lithium metal to
B. Intercalation of ions into graphite layers
C. De-intercalation of from graphite
D. Reduction of cobalt oxide

29 Why can a non-aqueous (organic) electrolyte be preferred in Li-ion batteries instead of an aqueous one?

Li-ion battery Medium
A. Aqueous electrolytes reduce the energy density unnecessarily
B. Water increases the risk of memory effect
C. Organic solvents conduct ions better than water
D. The high cell voltage would decompose water

30 In a fully charged lead-acid battery, the material present at the cathode (positive plate) is:

Lead storage battery Medium
A.
B.
C.
D.

31 As a lead-acid battery discharges, the specific gravity of the electrolyte decreases because:

Lead storage battery Medium
A. dissolves and thickens the acid
B. is consumed and water is produced
C. is generated at both electrodes
D. Water evaporates from the electrolyte

32 What makes Li-air batteries theoretically attractive compared to conventional Li-ion batteries?

Li-air battery Medium
A. Very high theoretical energy density using oxygen from air as cathode reactant
B. They avoid the formation of any discharge products
C. They operate without any electrolyte
D. They completely eliminate the need for a lithium anode

33 Which of the following fuels generally has the highest gross calorific value per unit mass?

Calorific value of fuels Medium
A. Petrol
B. Hydrogen
C. Coal
D. Natural gas (methane)

34 Which characteristic best distinguishes a primary cell from a secondary cell?

Primary cells Medium
A. Its cell reaction is irreversible and cannot be recharged
B. It always delivers a higher voltage
C. It can be recharged many times
D. It uses a solid electrolyte only

35 Which of the following is NOT an example of a secondary (rechargeable) battery?

Secondary batteries Medium
A. Li-ion battery
B. Ni-Cd battery
C. Lead-acid battery
D. Dry Leclanché cell

36 In a - fuel cell, what reaction occurs at the anode?

Fuel cells- principles, applications, advantages/disadvantages Medium
A.
B.
C.
D.

37 A key advantage of fuel cells over conventional heat engines is that they:

Fuel cells- principles, applications, advantages/disadvantages Medium
A. Convert chemical energy directly to electricity, bypassing the Carnot limit
B. Produce no reaction products at all
C. Operate only at very high temperatures for best efficiency
D. Store energy indefinitely without any fuel supply

38 Which of the following is a set of only secondary (derived) fuels?

energy sciences: fuels and its types Medium
A. Wood, crude oil, natural gas
B. Coal, petroleum, natural gas
C. Uranium, coal, biomass
D. Coke, petrol, coal gas

39 Which method of hydrogen production is considered 'green hydrogen' with essentially zero carbon emissions?

hydrogen energy (production, storage, safety aspects) and significance as a clean and sustainable energy carrier Medium
A. Steam reforming of natural gas
B. Electrolysis of water using renewable electricity
C. Partial oxidation of hydrocarbons
D. Coal gasification

40 A major safety concern in the storage and handling of hydrogen gas is that it:

hydrogen energy (production, storage, safety aspects) and significance as a clean and sustainable energy carrier Medium
A. Is highly toxic and corrosive to the lungs
B. Is denser than air and accumulates near the ground
C. Has a very wide flammability range and low ignition energy
D. Reacts violently with inert gases like nitrogen

41 In a bomb calorimeter experiment, g of a fuel raises the temperature of g of water by . The water equivalent of the apparatus is g. Taking the specific heat of water as J/gC, the gross calorific value of the fuel is approximately:

determination of calorific value Hard
A. kJ/g
B. kJ/g
C. kJ/g
D. kJ/g

42 A fuel contains hydrogen by mass. Its gross calorific value is cal/g. Given the latent heat of steam is cal/g, the net calorific value is closest to:

determination of calorific value Hard
A. cal/g
B. cal/g
C. cal/g
D. cal/g

43 In the proximate analysis of coal, a g air-dried sample loses g on heating at , loses a further g on heating at (covered), and leaves g ash after burning. The percentage of fixed carbon is:

analysis of coal Hard
A.
B.
C.
D.

44 Which statement correctly distinguishes ultimate analysis from proximate analysis of coal?

analysis of coal Hard
A. Proximate analysis determines sulphur and nitrogen while ultimate analysis determines fixed carbon
B. Ultimate analysis gives elemental composition (C, H, N, S, O) while proximate analysis gives moisture, volatile matter, ash, and fixed carbon
C. Both give the same data but ultimate analysis uses a bomb calorimeter
D. Ultimate analysis gives moisture and ash while proximate analysis gives elemental composition

45 During discharge of a Ni-Cd cell, the reactions are and . Which conclusion about the electrolyte concentration is correct?

Ni-Cd Hard
A. is produced overall, raising the electrolyte concentration
B. Water is the net product, diluting the electrolyte continuously
C. is consumed overall, so electrolyte concentration falls sharply
D. Net concentration stays essentially constant since it is consumed at one electrode and produced at the other

46 A key advantage of Ni-MH batteries over Ni-Cd batteries, apart from being cadmium-free, is that:

Ni-metal hydride battery Hard
A. They deliver a nominal cell voltage of V
B. They are non-rechargeable and thus safer to dispose
C. They offer higher energy density and reduced memory effect using a hydrogen-absorbing alloy negative electrode
D. They use a molten salt electrolyte enabling higher operating temperature

47 In a Li-ion cell with a cathode and graphite anode, during charging the correct movement of lithium is:

Li-ion battery Hard
A. deintercalates from graphite and intercalates into
B. Metallic Li is plated on the cathode while dissolves
C. is oxidized to at the anode
D. deintercalates from and intercalates into graphite

48 Why is metallic lithium generally avoided as the anode in commercial rechargeable Li-ion cells despite its high specific capacity?

Li-ion battery Hard
A. Metallic lithium cannot conduct electrons at room temperature
B. Repeated cycling promotes dendrite growth that can cause internal short circuits
C. Lithium metal has a higher reduction potential than graphite
D. Lithium metal reacts with the cathode to form only during discharge

49 The overall discharge reaction of a lead-acid cell is . As the cell discharges, the specific gravity of the electrolyte:

Lead storage battery Hard
A. Decreases, because is consumed and water is produced
B. Increases, because water is consumed at the anode
C. Remains constant, since sulphate is recycled
D. Increases, because dissolves into the electrolyte

50 A V lead-acid battery is built from series-connected cells. Given each cell has a nominal EMF of about V, and the standard EMF arises from cathode ( V) and anode ( V), the number of cells and theoretical cell EMF are:

Lead storage battery Hard
A. cells, V each
B. cells, V each
C. cells, V each
D. cells, V each

51 The Li-air battery attracts research interest primarily because:

Li-air battery Hard
A. It uses cheap lead electrodes with an aqueous acid
B. It operates without any electrolyte, eliminating leakage
C. Its theoretical specific energy approaches that of gasoline since oxygen is drawn from air rather than stored
D. It produces no discharge product at the cathode

52 A major technical challenge limiting practical non-aqueous Li-air batteries is that the discharge product :

Li-air battery Hard
A. Dissolves the lithium anode instantly
B. Is highly conductive and short-circuits the cell
C. Is insoluble and insulating, clogging the porous cathode and causing high overpotential
D. Is a gas that escapes, reducing coulombic efficiency

53 Two fuels A and B have the same gross calorific value per kilogram. Fuel A contains significantly more hydrogen than fuel B. Which fuel has the higher net calorific value and why?

Calorific value of fuels Hard
A. Fuel A, because water condensation adds to its usable heat
B. Fuel A, because hydrogen combustion releases extra heat
C. Both equal, since GCV is identical
D. Fuel B, because less hydrogen means less water formed and lower latent heat loss

54 Which characteristic fundamentally distinguishes a primary cell from a secondary cell at the electrochemical level?

Primary cells Hard
A. In primary cells the electrode reactions are not readily reversible by charging, so they cannot be efficiently recharged
B. Primary cells always use aqueous electrolytes while secondary cells use molten salts
C. Primary cells store more total energy than any secondary cell
D. Primary cells produce AC while secondary cells produce DC

55 A secondary battery has an energy efficiency defined as . If a cell is charged at an average V and discharged at an average V with a coulombic (charge) efficiency of , its energy efficiency is closest to:

Secondary batteries Hard
A.
B.
C.
D.

56 In an - alkaline fuel cell, the anode reaction is and the cathode reaction is . A distinctive thermodynamic advantage of the fuel cell over a heat engine burning the same is that:

Fuel cells- principles, applications, advantages/disadvantages Hard
A. It is not limited by the Carnot efficiency, converting chemical energy directly to electrical energy
B. It stores reactants internally like a battery, needing no fuel supply
C. It produces that can be captured for extra energy
D. Its efficiency increases without bound as temperature falls

57 For an - fuel cell, kJ/mol and kJ/mol for water formation. The maximum theoretical (thermodynamic) efficiency of the cell is:

Fuel cells- principles, applications, advantages/disadvantages Hard
A.
B.
C.
D.

58 "Green hydrogen" is distinguished from "grey hydrogen" chiefly by:

hydrogen energy (production, storage, safety aspects) and significance as a clean and sustainable energy carrier Hard
A. Being produced by steam reforming of methane without a catalyst
B. Production via electrolysis of water using renewable electricity, with no net emission
C. Having a green colorant added for safety identification
D. Being stored at higher pressure in steel cylinders

59 In the fission of , about MeV is released per fission. Given eV J and Avogadro's number /mol, the energy released by complete fission of mole ( g) of is closest to:

nuclear energy (principles of nuclear energy, sustainable energy production) Hard
A. J
B. J
C. J
D. J

60 Spintronic devices differ from conventional electronics because they exploit:

spintronics and its engineering applications Hard
A. The electron's spin (magnetic moment) in addition to its charge, as seen in giant magnetoresistance read heads
B. Only the mass of the electron to store data
C. The nuclear spin of the semiconductor lattice for conduction
D. Photon polarization instead of electrons
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