Category: Engineering Chemistry Objective Questions

Engineering Chemistry Questions and Answers for Experienced people focuses on “Oils and Fats – 2”.

1. The catalyst used in the addition of iodine is ____________
a) Ni/ Pt
b) Lewis acids
c) CH₃MgCl
d) HgCl₂
Answer: d
Clarification: The catalyst used in the addition of iodine is HgCl₂. Other catalyst that are mentioned cannot be used for this purpose.

2. Drying oils are used as the medium of paints and varnishes.
a) True
b) False
Answer: a
Clarification: Drying oils are used as the medium of paints and varnishes. When paints and varnishes are applied in thin layers, linseed oil quickly dries up to form a protective layer.

3. Which of the following is responsible for rancidity?
a) Alkalies
b) Ketones
c) Aldehydes
d) Alcohols
Answer: c
Clarification: Volatile acids and aldehydes are responsible for rancidity due to their offensive odour.

4. The number of milligrams of KOH required for the saponification of one gram of oil or fat is called ____________
a) Acid number
b) Iodine number
c) Richert-Meissl number
d) Saponification number
Answer: d
Clarification: The number of milligrams of KOH required for the saponification of one gram of oil or fat is called saponification number. The long chain fatty acids found in fats have a low saponification value because they have a relatively fewer number of carboxylic functional groups per unit mass of the fat as compared to short chain fatty acids.

5. Iodine number is defined as number of grams of iodine needed for the iodination of ________ gram/grams of oil or fat.
a) 1
b) 5
c) 100
d) 1000
Answer: c
Clarification: Iodine number is defined as number of grams of iodine needed for the iodination of 100 grams of oil or fat. Iodine numbers are often used to determine the amount of unsaturation in fatty acids. This unsaturation is in the form of double bonds, which react with iodine compounds. The higher the iodine number, the more C=C bonds are present in the fat.

6. Richert-Meissl number is defined as the volume of 0.1M KOH solution required for the neutralisation of _______ gram/grams of fat or oil.
a) 1
b) 5
c) 100
d) 1000
Answer: b
Clarification: Richert-Meissl number is defined as the volume of 0.1M KOH solution required for the neutralisation of 5grams of fat or oil. It is an indicator of how much volatile fatty acid can be extracted from fat through saponification.

7. Which of the following tells the amount of free fatty acids present in fat or oil?
a) Acid number
b) Iodine number
c) Saponification number
d) Richert-Meissl number
Answer: a
Clarification: Acid number tells the amount of free fatty acids present in fat or oil. It is the mass of potassium hydroxide (KOH) in milligrams that is required to neutralize one gram of chemical substance.

8. Which of the following helps in the classification of oils into drying, semi-drying and non-drying categories?
a) Acid number
b) Iodine number
c) Saponification number
d) Richert-Meissl number
Answer: b
Clarification: Iodine number helps in the classification of oils into drying, semi-drying and non-drying categories. Iodine numbers are often used to determine the amount of unsaturation in fatty acids. This unsaturation is in the form of double bonds, which react with iodine compounds. The higher the iodine number, the more C=C bonds are present in the fat.

9. Which of the following is of special value in testing the purity of butter and desi-ghee?
a) Acid number
b) Iodine number
c) Saponification number
d) Richert-Meissl number
Answer: d
Clarification: Richert-Meissl number is of special value in testing the purity of butter and desi-ghee. It is an indicator of how much volatile fatty acid can be extracted from fat through saponification.

10. The smaller is the saponification value, the higher will be the molecular weight of oil or fat.
a) True
b) False
Answer: a
Clarification: The smaller is the saponification value, the higher will be the molecular weight of oil or fat. The long chain fatty acids found in fats have a low saponification value because they have a relatively fewer number of carboxylic functional groups per unit mass of the fat as compared to short chain fatty acids.

areas of Engineering Chemistry for Experienced people,

Basic Engineering Chemistry Questions and Answers focuses on “Intermolecular Forces”.

1. Which of the following is a microscopic property?
a) Reactivity
b) Inter-molecular force
c) Boiling point
d) Kinetic energy
Answer: b
Clarification: Inter-molecular force is a microscopic property and all others are the macroscopic property. A macroscopic property describes the characteristics or behaviour of a sample which is large enough to see, handle, manipulate, weigh, etc. A microscopic property describes the behaviour of a much smaller sample of matter, an atom or molecule for instance.

2. Which of the following has the highest bond dissociation energy?
a) Covalent bond
b) Vander Waals forces
c) Dipole-dipole
d) Hydrogen bond
Answer: a
Clarification: Covalent Bond has the highest dissociation energy (400 kJ/mol) among the following options. Vander Waal’s forces are the weakest among the following.

3. The strength of Vander Waals forces depends upon ___________
a) Size of the molecule
b) Molecular structure
c) Number of electrons present in the molecule
d) All of the mentioned
Answer: d
Clarification: The strength of Vander Waals forces depends upon the size of the molecule, molecular structure and the number of electrons present in the molecule.

4. Arrange the following molecules in the order of increasing boiling point.
a) I₂ < Br₂ < Cl₂ < F₂
b) F₂ < Cl₂ < Br₂ < I₂
c) F₂ < Br₂ < Cl₂ < I₂
d) Cl₂ < F₂ < I₂ < Br₂
Answer: b
Clarification: The correct order of boiling point is F₂ < Cl₂ < Br₂ < I₂.
It is due to the highest electronegativity of fluorine atom.

5. Hydrogen bonding is maximum in ___________
a) Diethyl ether
b) Ethyl chloride
c) Ethanol
d) Triethylamine
Answer: c
Clarification: Hydrogen bonding is maximum in Ethanol. It is a volatile, flammable, colorless liquid with a slight chemical odor. It is used as an antiseptic, a solvent, a fuel, and due to its low freezing point, the active fluid in many alcohol thermometers.

6. Which of the following is not a necessary condition for the formation of intra-molecular hydrogen bonding?
a) A 5 or 6-membered ring should be formed
b) The ring should be planar
c) There should be minimum strain during the ring closure
d) There should be maximum strain during the ring closure
Answer: d
Clarification: The necessary conditions for the formation of intra-molecular hydrogen bonding are: 5 or 6-membered ring should be formed, the ring should be planar and there should be minimum strain during the ring closure.

7. Which of the following is the consequence of hydrogen bonding?
a) Abnormal boiling point
b) Solubility and Viscosity
c) Azeotropic behavior
d) All of the mentioned
Answer: d
Clarification: The consequences of hydrogen bonding are: Abnormal boiling point, solubility, viscosity and azeotropic behavior.

8. O-nitrophenol is more volatile than p-nitrophenol due to ___________
a) Inductive effect
b) Electromeric effect
c) Inter-molecular hydrogen bonding in O-nitrophenol
d) Intra-molecular hydrogen bonding in O-nitrophenol
Answer: d
Clarification: O-nitrophenol is more volatile than p-nitrophenol due to Intra-molecular hydrogen bonding in O-nitrophenol. Intra-molecular hydrogen bonding occurs within different parts of a single molecule.

9. Which of the following possess lowest energy?
a) NO
b) O₂
c) N₂
d) CO
Answer: c
Clarification: N₂ possesses the lowest bond energy among the following options.

10. At what temperature does the water molecules contract?
a) At 0⁰C
b) Below 0⁰C
c) At 4⁰C
d) Between 0⁰C and 4⁰C
Answer: d
Clarification: Water contracts when heated between 0₀C and 4₀C. In this range of temperature, all the water molecules breaks down to change its state.

To practice basic questions and answers on all areas of Engineering Chemistry,

Engineering Chemistry Problems focuses on ” B. E. T. Adsorption Isotherm”.

1. The B.E.T. theory was proposed in the year?
a) 1940
b) 1935
c) 1938
d) 1945
Answer: c
Clarification: Brunauer, Emmett and Teller proposed a theory in 1938 which is known as B.E.T. theory.

2. The B.E.T. theory was based on the ____________
a) Single layer adsorption
b) Multilayer adsorption
c) Double layer adsorption
d) None of the mentioned
Answer: b
Clarification: The B.E.T. theory was based on the multilayer adsorption. It aims to explain the physical adsorption of gas molecules on a solid surface and serves as the basis for an important analysis technique for the measurement of the specific surface area of a material.

3. Which of the following is an assumption for B.E.T theory?
a) The solid surface possess uniform, localised sites
b) The adsorption at one site does not affect adsorption at neighbouring site
c) Physical adsorption of adsorbate occurs resulting in the formation of multilayers
d) All of the mentioned
Answer: d
Clarification: The assumptions for B.E.T theory are – the solid surface possess uniform, localised sites, the adsorption at one site does not affect adsorption at neighbouring site and physical adsorption of adsorbate occurs resulting in formation of multilayers, etc.

4. The energy of adsorption in the first layer is ____________
a) Increasing
b) Decreasing
c) Constant
d) None of the mentioned
Answer: c
Clarification: The energy of adsorption in the first layer is constant. It aims to explain the physical adsorption of gas molecules on a solid surface and serves as the basis for an important analysis technique for the measurement of the specific surface area of a material.

5. The surface area available for the nth layer is equal to the coverage of ____________
a) (n-1)th layer
b) (n+1)th layer
c) nth layer
d) none of the mentioned
Answer: a
Clarification: The surface area available for the nth layer is equal to the coverage of (n-1)th layer. By application of the BET theory, it is possible to determine the inner surface of hardened cement paste.

6. In the B.E.T. equation, what does p⁰ denotes?
a) Pressure of the gas molecules
b) Unsaturated vapor pressure of the gas molecules
c) Saturated vapor pressure of the gas molecules
d) All of the mentioned
Answer: c
Clarification: In the B.E.T. equation, p⁰ denotes the saturated vapour pressure of the gas molecules at the same temperature.

7. According to B.E.T. equation, the plot of P/V(P⁰-P) versus P/P⁰ will yield a ____________
a) Straight line
b) Parabola
c) Hyperbola
d) Eclipse
Answer: a
Clarification: According to B.E.T. equation, the plot of P/V(P⁰-P) versus P/P⁰ will yield a straight line. By application of the BET theory, it is possible to determine the inner surface of hardened cement paste.

8. The B.E.T. theory is used in calculating the ____________
a) Surface area of adsorbate
b) Surface area of adsorbent only
c) Surface area of adsorbents and catalyst
d) None of the mentioned
Answer: c
Clarification: The B.E.T. theory is used in calculating the surface area of adsorbents and catalyst. By application of the BET theory, it is possible to determine the inner surface of hardened cement paste.

9. The surface area occupied by a single gas molecule is inversely proportional to the ____________
a) Molar mass of the gas adsorbed
b) Density of the liquefied gas
c) Volume of the gas
d) All of the mentioned
Answer: b
Clarification: The surface area occupied by a single gas molecule is inversely proportional to the density of the liquefied gas. Porous inorganic materials such as mesoporous silica and layered clay minerals have high surface areas of several hundred m²g⁻¹ calculated by the BET method.

10. The total surface area covered by all the molecules of the adsorbed gas is given by ____________
a) S = nβ/N_A
b) S = βN_A/n
c) S = nβN_A
d) S = N_A/nβ
Answer: c
Clarification: The total surface area covered by all the molecules of the adsorbed gas is given by S = nβN_A. The surface area occupied by a single gas molecule is inversely proportional to the density of the liquefied gas.

areas of Engineering Chemistry Problems,

Engineering Chemistry Multiple Choice Questions on “Electrophillic Substitution Reaction – 1”.

1. Which of the following is rate determining step in electrophilic substitution reaction?
a) Generation of electrophile
b) Attack by an electrophilic reagent on benzene ring
c) Formation of product
d) All of the mentioned
Answer: b
Clarification: Attack by an electrophilic reagent on benzene ring is a rate determining step in electrophilic substitution reaction. It is also the slowest step of the reaction.

2. Which of the following act as catalysis in the nitration of benzene?
a) Conc. HCl
b) Dil. HCl
c) Conc. H₂SO₄
d) Dil. H₂SO₄
Answer: c
Clarification: Conc. H₂SO₄ act as a catalysis in the nitration of benzene. Benzene is treated with a mixture of concentrated nitric acid and concentrated sulphuric acid at a temperature not exceeding 50°C.

3. Fuming sulphuric acid is the solution of _________% SO₃ in conc. H₂SO₄.
a) 10
b) 9
c) 8
d) 7
Answer: d
Clarification: Fuming sulphuric acid is the solution of 7% SO₃ in conc. H₂SO₄. It is also called Oleum which is produced in the contact process, where sulphur is oxidized to sulphur trioxide which is subsequently dissolved in concentrated sulphuric acid.

4. Which of the following is the necessary condition for desulphonation?
a) Remove volatile hydrocarbon by steam distillation
b) Low concentration of water
c) High concentration of sulphonating agent
d) A large excess of fuming sulphuric acid
Answer: a
Clarification: The necessary condition for desulphonation is to Use dilute acid, high concentration of water and remove volatile hydrocarbon by steam distillation.

5. Which of the following act as electrophile in halogenation?
a) Nitronium ion
b) Sulphonium ion
c) Halonium ion
d) Acylium ion
Answer: c
Clarification: Halonium ion act as electrophile in halogenation. Nitronium ion is used in nitration. Sulphonium ion is used in sulphonation. Acylium ion is used in acylation.

6. Aromatic bromination catalyzed by the Lewis acid thalium acetate gives ___________
a) Para isomer
b) Ortho isomer
c) Meta isomer
d) Para and ortho isomer
Answer: a
Clarification: Aromatic bromination catalyzed by the Lewis acid thalium acetate gives only para isomer. It is not Ortho and meta directing.

7. The reaction in which benzene reacts with alkyl halide in the presence of a lewis acid as a catalyst to produce alkylbenzene is known as ___________
a) Nitration
b) Halogenation
c) Friedel-Crafts Acylation
d) Friedel-Crafts Alkylation
Answer: d
Clarification: The reaction in which benzene reacts with alkyl halide in the presence of a lewis acid as a catalyst to produce alkylbenzene is known as Friedel-Crafts Alkylation. With anhydrous ferric chloride as a catalyst, the alkyl group attaches at the former site of the chloride ion.

8. Which of the following is not a product of the reaction of benzene with CH₃Cl and AlCl₃?
a) Toulene
b) Isopropyl benzene
c) O-xylene
d) P-xylene
Answer: b
Clarification: p-xylene is not a product of reaction of benzene with CH₃Cl and AlCl₃. Toulene, isopropyl benzene and O-xylene are the products of such reaction.

9. The product of Friedel-Crafts Acylation reactions are ___________
a) Alkylbenzene
b) Alkylamine
c) Arylketone
d) Halobenzene
Answer: c
Clarification: The product of Friedel-Crafts Acylation reactions are Arylketone. The acylated products may easily be converted to the corresponding alkanes via Clemmensen Reduction or Wolff-Kishner Reduction.

10. How will you convert benzene into n-propyl benzene?
a) Friedel-Crafts Alkylation
b) Friedel-Crafts Acylation
c) Friedel-Crafts Alkylation followed by clemmensen reduction
d) Friedel-Crafts Acylation followed by clemmensen reduction
Answer: d
Clarification: Friedel-Crafts Acylation followed by clemmensen reduction of ketone will give n-propyl benzene. Clemmensen reduction is a chemical reaction described as a reduction of ketones (or aldehydes) to alkanes using zinc amalgam and hydrochloric acid.

Engineering Chemistry Multiple Choice Questions on “Laws of Photochemistry”.

1. __________ is also known as the Principle of Photochemical Activation.
a) Grothus–Draper law
b) Lambert’s law
c) Draper law
d) Stark law
Answer: a
Clarification: Grothus–Draper law is also known as the Principle of Photochemical Activation. This law states that only that light which is absorbed by a system is responsible for doing a photochemical change.

2. The absorbed radiation does not necessarily cause a chemical reaction.
a) True
b) False
Answer: a
Clarification: Yes, the absorbed radiation does not necessarily cause a chemical reaction. If the environment is not conducive for the molecules to react, then the light energy will remain unused or in some cases may be re-emitted as heat or light.

3. When a beam of light is allowed to pass through a transparent medium, the rate of decrease of intensity with the thickness of medium is __________ to the intensity of the light.
a) inversely proportional
b) directly proportional
c) equal
d) not related
Answer: b
Clarification: As per Lambert’s law, when a beam of light passes through a transparent medium, the rate of decrease of intensity with the thickness of medium is directly proportional to the intensity of the light. Mathematically, it may be stated as follows: -dI/t=kI.

4. The intensity of a beam of monochromatic light ___________ with the increase in the concentration of the absorbing substance arithmetically.
a) decrease exponentially
b) increase exponentially
c) decrease linearly
d) increase linearly
Answer: a
Clarification: As per Beer’s Law, the intensity of incident light decreases exponentially with the increase in concentration of the absorbing substance arithmetically. Mathematically, it is shown as follows: I = I_o/e^kc.

5. __________ is also known as Principle of Quantum Activation.
a) Lambert’s law
b) Beer’s law
c) Stark-Einstein law
d) Stark law
Answer: c
Clarification: Stark-Einstein law is also known as the Principle of Quantum Activation. It states that in a primary photochemical process, only one molecule is activated for every photo of light absorbed by the chemical system.

6. When a molecule absorbs a photon, it is necessary that only one molecule should react.
a) True
b) False
Answer: b
Clarification: When a molecule absorbs a photon, it is not necessary that only one molecule should react. It may or may not react or may cause the reaction of many molecules through a chain mechanism.

7. Beer-Lambert law is applicable if ____________
a) temperature changes
b) dilute solution is used
c) non-monochromatic radiation is used
d) temperature varies linearly
Answer: b
Clarification: Beer-Lambert law is not applicable if temperature changes during measurements. It is also not applicable if non-monochromatic radiation is used. It is applicable only to dilute solutions.

8. When light falls on a cell containing a reaction mixture __________ component of light is responsible for producing chemical reaction.
a) absorbed
b) adsorbed
c) transmitted
d) reflected
Answer: a
Clarification: When light falls on a cell containing a reaction mixture, some light is absorbed and the remaining light is transmitted. Transmitted light is chemically ineffective whereas absorbed component of light is capable of producing chemical reaction.

9. Grothus – Draper law is __________ in nature.
a) purely qualitative
b) quantitative
c) qualitative and quantitative
d) non-acceptable
Answer: a
Clarification: Grothus – Draper law is qualitative in nature. It does not give us any idea about the relation between absorbed radiations and molecules undergoing change.

10. Stark-Einstein studied the __________ aspects of photochemical reactions by application of quantum theory of light.
a) qualitative
b) quantitative
c) geometrical
d) qualitative and quantitative
Answer: b
Clarification: Stark-Einstein studied the quantitative aspects of photochemical reactions by application of the quantum theory of light. They observed that each molecule taking part in the reaction absorbs only one photon of light.