Category: Engineering Chemistry Objective Questions

Engineering Chemistry Multiple Choice Questions on “Surface Tension”.

1. The unit of surface tension in the CGS system is ____________
a) N/m
b) Kg/cm
c) Dynes/cm
d) Dynes/m
Answer: c
Clarification: The unit of surface tension in CGS system is dynes/cm. It is N/m in S.I. system. Surface tension is the elastic tendency of a fluid surface which makes it acquire the least surface area possible.

2. The apparatus used for the determination of surface tension of a liquid is ____________
a) Oedometer
b) Stalagmometer
c) Consolidometer
d) None of the mentioned
Answer: b
Clarification: The apparatus used for the determination of surface tension of a liquid is called stalagmometer. It is equivalent to force per unit length.

3. Stalagmometer is cleaned to remove grease with the help of ____________
a) Chromic acid
b) Sulphuric acid
c) Distilled water
d) Tartaric acid
Answer: a
Clarification: Stalagmometer is cleaned to remove grease with the help of chromic acid. It is used for the determination of surface tension.

4. The surface tension of water at 25⁰C is ____________
a) 90.0 dynes/cm
b) 45.63 dynes/cm
c) 82.5 dynes/cm
d) 72.14 dynes/cm
Answer: d
Clarification: The surface tension of water at 25⁰C is 72.14 dynes/cm. It is a standard value.

5. On increasing the temperature, the kinetic energy of the liquid molecules ____________
a) Increases
b) Decreases
c) Remains constant
d) None of the mentioned
Answer: a
Clarification: On increasing the temperature, the kinetic energy of the liquid molecules also increases. At high temperatures, randomness increases.

6. In case of water and glass, we get a concave meniscus because the adhesive force between water and glass are _______________ than the cohesive forces between water molecules.
a) Weaker
b) Stronger
c) Same
d) None of the mentioned
Answer: b
Clarification: In the case of water and glass, we get a concave meniscus because the adhesive force between water and glass are stronger than the cohesive forces between water molecules.

7. Shapes of drops of liquid are spherical because of ____________
a) Viscosity
b) Conductivity
c) Absorption
d) Surface tension
Answer: d
Clarification: Shapes of drops of liquid are spherical because of surface tension as it reduces the surface area to a minimum.

8. Select the incorrect statement from the following option.
a) In case of mercury and glass, we observe a convex meniscus
b) Surface tension is responsible for the rise and fall of the capillary tubes
c) If two drops encounter each other, they tend to repel each other
d) All of the mentioned
Answer: c
Clarification: If two drops encounter each other, they tend to coalesce into a large drop. All the other options are correct. In the case of mercury and glass, we observe a convex meniscus and Surface tension is responsible for the rise and fall of the capillary tubes.

9. On increasing the temperature, the surface tension of the liquid ____________
a) Increases
b) Decreases
c) Remains constant
d) None of the mentioned
Answer: b
Clarification: On increasing the temperature, the surface tension of the liquid decreases. It is inversely proportional to the temperature.

10. Which of the following is an application of surface tension?
a) Use of soaps and detergents as cleansing agents
b) Molecular structure can be elucidated by surface tension measurements through parachor values
c) Surfactants are incorporated in preparations like toothpaste
d) All of the mentioned
Answer: d
Clarification: Use of soaps and detergents as cleansing agents, molecular structure can be elucidated by surface tension measurements through parachor values and surfactants are incorporated in preparations like toothpaste are the applications of surface tension.

Engineering Chemistry Multiple Choice Questions on “Electronic Spectroscopy”.

1. The electronic spectra in the visible range span is __________
a) 25000-72000 cm^-1
b) 25000-50000 cm^-1
c) 12500-25000 cm^-1
d) 15000-30000 cm^-1
Answer: c
Clarification: The electronic spectra in the visible range span 12500-25000 cm^-1 and in the UV region span 25000-72000 cm^-1.

2. Which of the following transitions are of weak intensities and lie in the visible region?
a) n→n^*
b) σ→σ^*
c) π→π^*
d) n→σ^*
Answer: a
Clarification: n→n^* transitions are of weak intensities and lie in the visible region.

3. Arrange the various electronic transitions in the order of increasing energy.
a) n→σ^* < π→π^* < n→π^* < σ→σ^*
b) n→π^* < π→π^* < n→σ^* < σ→σ^*
c) n→σ^* < n→π^* < π→π^* < σ→σ^*
d) σ→σ^* < π→π^* < n→π^* < n→σ^*
Answer: b
Clarification: The correct order is- n→π^* < π→π^* < n→σ^* < σ→σ^*.

4. What is the position of the band of alkanes?
a) 190 nm
b) 185 nm
c) 217 nm
d) 150 nm
Answer: d
Clarification: The position of the band of alkanes is ≈150 nm. Alkanes refer to any of the series of saturated hydrocarbons including methane, ethane, propane, and higher members.

5. Which of the following organic compound shows transition due to conjugation?
a) Alkenes
b) Saturated aliphatic ketones
c) Conjugated dienes
d) Alkanes
Answer: c
Clarification: Conjugated dienes shows the transitions of low energy and is due to conjugation.

6. Which of the following is not an auxochrome group?
a) –OH
b) –SH
c) –OR
d) –O₂
Answer: d
Clarification: Auxochrome is the color enhancing group. –O₂ is not an example of auxochrome. -OH, -SH and -OR are examples of auxochrome.

7. Which of the following shift leads to the decreased intensity of absorption?
a) Hypochromic
b) Hyperchromic
c) Hypsochromic
d) Bathochromic
Answer: a
Clarification: Hypochromic shift leads to the decreased intensity of absorption. Hypochromicity describes a material’s decreasing ability to absorb light. Hyperchromicity is the material’s increasing ability to absorb light.

8. Which of the following is an application of electronic spectroscopy?
a) Detection of impurities
b) Control of purification
c) Study of kinetics of the chemical reaction
d) All of the mentioned
Answer: d
Clarification: Detection of impurities, control of purification, study of the kinetics of the chemical reaction, determination of molecular weight and determination of unknown concentration are the applications of electronic spectroscopy.

9. What will be the absorbance if %T = 80?
a) 0.5
b) 0.05
c) 0.097
d) 0.97
Answer: c
Clarification: Absorbance (A) = log(1/T) = log(100/80) = 0.097

10. Which of the following is a limitation of the Lambert-Beer’s law?
a) Scattering of light due to particles
b) Fluorescence of sample
c) Non-monochromatic radiation
d) All of the mentioned
Answer: d
Clarification: Scattering of light due to particles, fluorescence of the sample and non-monochromatic radiation are some of the limitations of Lambert-Beer’s law. It relates the attenuation of light to the properties of the material through which the light is traveling.

Engineering Chemistry Multiple Choice Questions on “Pseudo Order Reaction”.

1. Reactions which are bimolecular yet following ___________ order kinetics are called pseudo unimolecular reaction.
a) Zero
b) First
c) Second
d) Third
Answer: b
Clarification: Reactions that are bimolecular yet following first order kinetics are called pseudo unimolecular reaction. Pseudo means pretentious. Inversion of cane sugar is an example of pseudo first order reaction.

2. Which of the following is an example of pseudo first order reaction?
a) Saponification of ester
b) Oxidation of hydrogen bromide
c) Gaseous decomposition of hydrogen iodide
d) Inversion of cane sugar
Answer: d
Clarification: Inversion of cane sugar is an example of pseudo first order reaction. All the other options are not the example of pseudo first order reaction.

3. Which concentration plot is linear for a first order reaction? (A is one of the reactant)
a) [A] versus time
b) [A]² versus time
c) Ln[A] versus time
d) √[A] versus time
Answer: c
Clarification: The ln[A] versus time plot is linear and other graphs are curved for a first order reaction. For a zero order reaction, [A] versus time concentration plot is linear. For a second order reaction, 1/[A] versus time concentration plot is linear.

4. Based on the collision model, the atoms at the top of the potential energy hill are called ___________
a) Transition state
b) Energetic atom
c) Steric factor
d) Activation energy
Answer: a
Clarification: Based on the collision model, the atoms at the top of the potential energy hill are called transition state. The transition state is the state corresponding to the highest energy along the reaction coordinate. It has more free energy in comparison to the substrate or product; thus, it is the least stable state.

5. What does termolecular refer to?
a) 2 molecules colliding
b) 3 molecules colliding
c) 4 molecules colliding
d) 5 molecules colliding
Answer: b
Clarification: Termolecular means a collision of three molecules. Ter refers to three.

6. For a certain reaction, the rate = k[NO]²[O₂], when the initial concentration of NO is tripled, the initial rate ___________
a) Increases by a factor of nine
b) Increases by a factor of three
c) Increases by a factor of six
d) Decreases by a factor of nine
Answer: a
Clarification: For a certain reaction, the rate = k[NO]²[O₂], when the initial concentration of NO is tripled, the initial rate increases by a factor of nine. Here, the reaction is of the order 3.

7. In a series of reactions, the rate determining step is ___________
a) Simplest
b) Fast and complex
c) Fastest
d) Slowest
Answer: d
Clarification: In a series of reactions, the rate determining step is the slowest step. The rate determining step is the slowest step of a chemical reaction that determines the speed (rate) at which the overall reaction proceeds.

8. Threshold energy is the sum of ___________
a) Internal energy and external energy of reactants
b) Activation energy and external energy of reactants
c) Activation energy and internal energy of reactants
d) Activation energy and thermal energy
Answer: c
Clarification: Threshold energy is the sum of activation energy and internal energy of reactants. The threshold energy for the production of a particle is the minimum kinetic energy a pair of traveling particles must have when they collide.

Engineering Chemistry Multiple Choice Questions on “Characterisation of Polymer Samples”.

1. Which of the following technique is used to measure the number of conjugated double bonds and aromatic conjugation within the various molecules?
a) Fourier transform infrared
b) Differential scanning calorimetry
c) U/V Visible spectroscopy
d) Thermo gravimetric analysis
Answer: c
Clarification: UV/ Visible spectroscopy is used to measure the number of conjugated double bonds and aromatic conjugation within the various molecules.

2. Fourier transform infrared spectroscopy is used to study ____________
a) Quantitative determination of additives in polymers
b) Curing and degradation behaviour of cross-linked polymers
c) Determination of volatilities of plasticizers
d) Analysis of structural imperfections on the surface
Answer: b
Clarification: Fourier transform infrared spectroscopy is used to study the curing and degradation behaviour of cross-linked polymers.

3. Atomic force microscopy comes under the category of ____________
a) Spectral analysis
b) Thermal analysis
c) Mechanical testing
d) Morphological analysis
Answer: d
Clarification: Atomic force microscopy comes under the category of morphological analysis.

4. Which of the following is useful for determination of volatilities of plasticizers and other additives?
a) Thermo gravimetric analysis
b) Differential scanning calorimetry
c) Scanning electron microscopy
d) Atomic force microscopy
Answer: a
Clarification: Thermo gravimetric analysis is useful for determination of volatilities of plasticizers and other additives.

5. Differential scanning calorimetry is useful for determining the ____________
a) Melting temperature, glass transition temperature, heat of fusion etc
b) Volatilities of plasticizers and other additives
c) Quantitative determination of additives in polymers
d) Structural imperfections
Answer: a
Clarification: Differential scanning calorimetry is useful for determining the melting temperature, glass transition temperature, heat of fusion etc.

6. Differential scanning calorimetry comes under the category of ____________
a) Spectral analysis
b) Morphological analysis
c) Thermal analysis
d) Geological analysis
Answer: c
Clarification: Differential scanning calorimetry comes under the category of thermal analysis.

7. Which of the following is used as a criterion in quality control?
a) X-ray diffraction
b) Mechanical testing
c) Wetting properties
d) Spectral analysis
Answer: b
Clarification: Mechanical testing is used as a criterion in quality control. It shows whether a material or part is suitable for its intended application by measuring properties such as elasticity, hardness, fracture toughness, impact resistance, and the fatigue limit.

8. The study of fracture surfaces of polymeric material is done using ____________
a) Atomic force microscopy
b) X-ray diffraction
c) Thermo gravimetric analysis
d) Scanning electron microscopy
Answer: d
Clarification: The study of fracture surfaces of polymeric material is done using scanning electron microscopy.

9. A hydrophobic surface with low free surface energy gives a ____________ with water.
a) Low contact angle
b) High contact angle
c) Zero contact angle
d) Extremely low contact angle
Answer: b
Clarification: A hydrophobic surface with low free surface energy gives a high contact angle with water.

10. An index of crystallinity can be obtained from the ratio of the integrated intensity of the crystalline peaks to the total area under the XRD curve.
a) True
b) False
Answer: a
Clarification: An index of crystallinity can be obtained from the ratio of the integrated intensity of the crystalline peaks to the total area under the XRD curve.

Engineering Chemistry Multiple Choice Questions on “Organic Conducting Polymers”.

1. Which of the following is used for making rechargeable batteries?
a) Polypyrrole
b) Polyester
c) Polyaniline
d) Polyacrylonitrile
Answer: c
Clarification: Polyaniline is used for making rechargeable batteries in the shape of flat buttons or as laminated rolled films.

2. The advantage of using conducting polymers in place metals is their ____________
a) Cost
b) Light-weight
c) Thermal conductivity
d) Solubility
Answer: b
Clarification: The advantage of using conducting polymers in place metals is their light-weight and they do not corrode.

3. During the polymerisation of polyaniline, the sequence of the colour change is ____________
a) Green >> copper tint >> blue green >> light blue
b) Light blue >> blue green >> copper tint >> green
c) Copper tint >> blue green >> green >> light blue
d) Blue green >> green >> light blue >> copper tint
Answer: b
Clarification: During the polymerisation of polyaniline, the sequence of the colour change is Light blue >> blue green >> copper tint >> green.

4. The precipitate is dried under vacuum at 60-80 ⁰C for ____________
a) 1 hour
b) 2 hours
c) 5 hours
d) 8 hours
Answer: d
Clarification: The precipitate is dried under vacuum at 60-80 ⁰C for 8hours for complete dehydration process.

5. The color of emeraldine salt which is obtained is ____________
a) Copper tint
b) Blue green
c) Green
d) Light blue
Answer: c
Clarification: The color of emeraldine salt which is obtained is green. The emeraldine salt form of polyaniline is highly electrically conducting.

6. The final washings of the salt is done with ____________
a) Distilled water
b) Diethyl ether
c) Methanol
d) Acetone
Answer: b
Clarification: The final washings of the salt is done with diethyl ether for cleaning it completely.

7. Conducting polymers having conjugation is a type of intrinsically conducting polymers.
a) True
b) False
Answer: a
Clarification: Conducting polymers having conjugation is a type of intrinsically conducting polymers. They do not conduct extrinsically.

8. Which of the following is not true for intrinsically conducting polymers?
a) Low conductivities
b) Poor mechanical strength
c) Improcessability
d) Good storage stability
Answer: d
Clarification: Intrinsically conducting polymers have poor storage stability leading to its loss in conductivity.

9. Select the incorrect statement from the following option.
a) Conductive element filled polymer possess good bulk conductivity
b) Conductive element filled polymer are generally high in cost
c) Conductive element filled polymer are light in weight
d) Conductive element filled polymer are mechanically durable and strong
Answer: b
Clarification: Conductive element filled polymer are generally low in cost. All the other options are correct.

10. Which of the following is not an application of conducting polymers?
a) Rechargeable batteries
b) Analytical sensors
c) Electronics
d) Adhesives
Answer: d
Clarification: Rechargeable batteries, analytical sensors, electronics are some of the applications of conducting polymers.

11. Emeraldine base form of polyaniline is used as a resist for lithography.
a) True
b) False
Answer: a
Clarification: Emeraldine base form of polyaniline is used as a resist for lithography. The synthesis of polyaniline nano structures is facile.

12. Bakelite is ____________
a) Gel
b) Gas
c) Solid
d) Liquid
Answer: c
Clarification: Bakelite is soild. It is a thermosetting phenol formaldehyde resin, formed from a condensation reaction of phenol with formaldehyde.

Engineering Chemistry Multiple Choice Questions on “Pulverised Coal”.

1. How can we increase the rate of combustion of solid fuel?
a) By storing it in the right conditions
b) By the process of pulverisation
c) By removing the impurities present in it
d) By blending of coal
Answer: b
Clarification: The rate of combustion can be increased by bringing the air in contact with the fuel. The coal powder is pulverised from 75-85% below 74µm. Blending of coal produces a good quality of coal. The impurities are somewhat useful.

2. On what factors does the burning of pulverised coal depends?
a) The calorific value of fuel
b) Bulk density
c) Percentage of volatile matter
d) On the texture of coal
Answer: c
Clarification: Coal having high volatile matter is used for making pulverised coal. As soon as it is fired, the volatile matter starts burning which helps in increasing the rate of combustion. The degree of fitness of particles also helps in the burning of pulverised coal.

3. In which state does the pulverised coal burns?
a) Gaseous
b) Liquid
c) Solid
d) Colloidal
Answer: a
Clarification: The air-fuel mixture of the pulverised coal is sent along with air under suitable burner which burns just like the gaseous fuel. This is because of the mixing of coal powder with air.

4. How can we transport pulverised coal?
a) Maintaining suitable conditions of temperature and pressure
b) By suitable packaging of the coal
c) With the help of air compressors
d) By forcing a stream of air
Answer: d
Clarification: It becomes easy to handle and transport the pulverised coal if a strong stream of air is continuously passed though the coal powder. This work can also be done by using screw conveyer to keep the pulverised coal fresh.

5. The rate of combustion cannot be easily controlled in combustion of pulverised coal.
a) True
b) False
Answer: b
Clarification: The combustion of pulverised coal occurs in gaseous state due to which its rate of combustion can be controlled easily. This also helps us to increase the calorific value of the coal depending on its rate of combustion.

6. The combustion process of pulverised coal is ________________
a) Non-uniform and incomplete
b) Non-Uniform and complete
c) Uniform and complete
d) Uniform and incomplete
Answer: c
Clarification: Pulverised coal intimately mixes with air and undergoes uniform and complete combustion. This happens because the pulverised coal is sent along with suitable burners for its combustion.

7. Which of the low grade coal is suitable for pulverising?
a) Coals containing high moisture content
b) Coals with more percentile of impurities
c) Coals with low fixed carbon rating
d) Coals containing high percentile of ash
Answer: d
Clarification: Ash contains many minerals, due to which when coal powder is allowed to mix with air most of its minerals form oxides and escapes out, due to which it helps in increasing the rate of combustion of coal. This process is very useful for Indian coals because they contain a lot of ash content in them.

8. Which type of burners are used for mixing of coal powder and air?
a) Turbulent burner
b) Pressure jet burner
c) Rotatory cup burner
d) Dual fuel burner
Answer: a
Clarification: Turbulent burner is an atomising burner which is used to mix fuel and air to produce a flow. Dual fuel burner cannot be used in this case as the physical state of both are different.

9. Which type of firing technique is employed for pulverised coal?
a) Oxidation firing
b) Reduction firing
c) Front wall firing
d) Raku firing
Answer: c
Clarification: The pulverised coal is burnt along the front side of the burner. It can be done in more three ways, i.e. side wall firing, U-flame firing and corner firing respectively. U-flame firing is not used so much as it produces a very long flame.

10. Which method is used for reducing fly ash?
a) Dry bottom
b) Slag-tap
c) Cyclone burner
d) Corner firing
Answer: b
Clarification: Fly ash is the ash produced by burning the pulverised coal. 75% of fly ash is deposited around the surrounded places. When the pulverised coal is burnt is slag-tap furnace, its flame is directed towards and sweeps over the bed of molten slag where the particles of ash are caught.