Category: Engineering Chemistry Objective Questions

Engineering Chemistry Multiple Choice Questions on “Reverse Osmosis”.

1. The basis of reverse osmosis is _____________
a) Osmotic pressure is greater than the hydrostatic pressure
b) Osmotic pressure is equal to the hydrostatic pressure
c) Hydrostatic pressure is greater than the osmotic pressure
d) Osmotic pressure does not exist
Answer: c
Clarification: The basis of reverse osmosis is that the hydrostatic pressure is greater than osmotic pressure. It is a process by which a solvent passes through a porous membrane in the direction opposite to that for natural osmosis when subjected to a hydrostatic pressure greater than the osmotic pressure.

2. Select the incorrect statement from the following option.
a) Osmosis is the phenomenon by virtue of which flow of solvent takes placefrom low concentration to high concentration through a semi-permeable membrane
b) The flow continues till the concentration is equal on both the sides
c) The driving force of osmosis is osmotic pressure
d) Osmosis is used for the treatment of waste water
Answer: d
Clarification: Reverse osmosis is used for the treatment of waste water. All the other options are correct. Osmosis is the phenomenon by virtue of which flow of solvent takes placefrom low concentration to high concentration through a semi-permeable membrane.

3. Semi-permeable membrane is selective membrane which does not permit the passage of dissolved ________ particles.
a) Solvent
b) Solute
c) Anhydrous
d) Saturated
Answer: b
Clarification: Semi-permeable membrane is selective membrane which does not permit the passage of dissolved solute particles. It is a type of biological or synthetic, polymeric membrane that will allow certain molecules or ions to pass through it by diffusion

4. Which of the following is not used for semi-permeable membrane?
a) Polymethyl sulphate
b) Cellulose acetate
c) Polyamide polymer
d) Polymethyl acrylate
Answer: a
Clarification: Polymethyl sulphate is not used for semi-permeable membrane. Cellulose acetate, polyamide polymer and polymethyl acrylate are used as semi-permeable membranes.

5. The pressure which is applied to separate the water from its contaminants is of the order ___________
a) 5-10 kg/cm²
b) 15-40 kg/cm²
c) 50-100 kg/cm²
d) 100-150 kg/cm²
Answer: b
Clarification: The pressure which is applied to separate the water from its contaminants is of the order 15-40 kg/cm². It does not require very high pressure.

6. The process of reverse osmosis is also known as ___________
a) Hyper-filtration
b) Double-filtration
c) Double-osmosis
d) Hyper-osmosis
Answer: a
Clarification: The process of reverse osmosis is also known as super- or hyper-filtration. It is a process by which a solvent passes through a porous membrane in the direction opposite to that for natural osmosis when subjected to a hydrostatic pressure greater than the osmotic pressure.

7. Which of the following is not an application of reverse osmosis?
a) Desalination
b) Reclamation of minerals
c) For dialysis in hospitals
d) For industrial use
Answer: d
Clarification: Reverse osmosis is not used for industrial purpose. All the other options are correct. It is used for desalination, reclamation of minerals and for dialysis in hospitals.

8. Select the incorrect statement about reverse osmosis from the following option.
a) It is simple and reliable process
b) It is relatively energy efficient
c) It operates at a comparatively high temperature
d) The life of an SPM is about 2 years and it can be easily replaced within a few minutes
Answer: c
Clarification: Reverse osmosis operates at a comparatively low temperature. All the other options are correct. It is simple and reliable process, relatively energy efficient. The life of an SPM is about 2 years and it can be easily replaced within a few minutes.

9. The pH for the potable water should be in the range of ___________
a) 5-6
b) 7-8.5
c) 9-10
d) 12-13
Answer: b
Clarification: The pH for the potable water should be in the range of 7-8.5. It should not be acidic and also should not have a high value of basicity. Hence, it’s value should be in the neutral range.

10. The total hardness of the potable water should be less than ___________
a) 500 ppm
b) 700 ppm
c) 900 ppm
d) 1000 ppm
Answer: a
Clarification: The total hardness of the potable water should be less than 500 ppm. Water having hardness more than 500 ppm is not safe for consumption.

Engineering Chemistry Multiple Choice Questions on “Soaps”.

1. Soaps are _____________ based soapy detergents.
a) Water
b) Kerosene
c) Oil
d) Acid
Answer: c
Clarification: Soaps are oil based soapy detergents. Soaps for cleansing are obtained by treating vegetable or animal oils and fats with a strongly alkaline solution.

2. The saponification of a fat or oil is done using _______________ solution for hot process.
a) KOH
b) NaOH
c) HCl
d) NaCl
Answer: b
Clarification: The saponification of a fat or oil is done using NaOH solution for hot process. Saponification to the sodium salt of myristic acid takes place with NaOH in water. NaOH gives hard soaps.

3. The saponification of a fat or oil is done using _______________ solution for cold process.
a) KOH
b) NaOH
c) HCl
d) NaCl
Answer: a
Clarification: The saponification of a fat or oil is done using KOH solution for cold process. When potassium hydroxide (KOH) is used, a soft soap is formed. It cannot be used in hard water.

4. Soft soaps are the limitation of hot process because of their ____________
a) High alkalinity
b) Low alkalinity
c) Low solubility in water
d) High solubility in water
Answer: d
Clarification: Soft soaps are the limitation of the hot process because of their greater solubility in water. When potassium hydroxide (KOH) is used, a soft soap is formed by the cold process. It cannot be used in hard water.

5. Select the incorrect statement from the following option.
a) Hard soaps are the sodium carboxylates
b) Soft soaps are potassium carboxylates
c) Hard soaps are manufactured by cold process
d) Example of soft soap – shampoo and shaving cream
Answer: c
Clarification: Hard soaps are manufactured by hot process and soft soaps are manufactured by cold process.

6. Which of the following is the residual product in the formation of soap?
a) Glyceraldehyde
b) Glycerol
c) Glycerine
d) Acrylonitrile
Answer: b
Clarification: Glycerol is the residual product in the formation of soap. The immediate product is called an orthoester:

7. Which of the following is a typical soap molecule?
a) Calcium stearate
b) Potassium permanganate
c) Sodium bicarbonate
d) Sodium stearate
Answer: d
Clarification: Sodium stearate is a typical soap molecule. Sodium stearate is the sodium salt of stearic acid. Sodium stearate has both hydrophilic and hydrophobic parts, the carboxylate and the long hydrocarbon chain, respectively.

8. Select the correct statement from the following options.
a) The soap micelle is unstable due to positive charge on its head
b) The soap micelle is stable due to positive charge on its head
c) The soap micelle is unstable due to negative charge on its head
d) The soap micelle is stable due to negative charge on its head
Answer: d
Clarification: The soap micelle is stable due to the negative charge on its polar head. It carries a negative charge due to attractive forces.

9. Soaps do not act efficiently in hard water and in acidic solution.
a) True
b) False
Answer: a
Clarification: Soaps do not act efficiently in hard water and in acidic solution due to their softness as compared to detergents. Soaps are the soft detergents and cannot be used in water containing calcium and magnesium salts.

Engineering Chemistry Multiple Choice Questions on “Valence Bond Theory”.

1. Valence Bond Theory was developed in the year?
a) 1916
b) 1927
c) 1930
d) 1932
Answer: b
Clarification: The Valence Bond Theory was developed in 1927 by Heitler and London.

2. According to VBT, the formation of a stable bond requires _____________
a) The electrons should have opposite spins
b) The two atoms should be close to each other
c) The greater overlapping of the electron clouds
d) All of the mentioned
Answer: d
Clarification: According to VBT, when two atoms come closer to each other with opposite electron spins, due to mutual rearrangements (or overlapping) of their electron clouds, energy changes are produced.

3. The s-orbital does not show preference to any direction because _____________
a) It is the smallest orbital
b) It is present in every atom
c) It is spherically symmetric
d) It is the first orbital
Answer: c
Clarification: The s-orbital is spherically symmetric in shape so it does not show preference to any direction. It is the same from all the directions.

4. The p-orbital is in the shape of a _____________
a) Sphere
b) Dumbbell
c) Pear-shaped lobe
d) None of the mentioned
Answer: b
Clarification: The p-orbital is in the shape of a Dumbbell. It has 2 lobes that are pointing in opposite directions.

5. The Valence Bond Theory does not explain the paramagnetic nature of oxygen molecule.
a) True
b) False
Answer: a
Clarification: Oxygen molecule is paramagnetic in nature, although it does not contain unpaired electrons which is not explained in VBT.

6. According to VBT, the direction of a bond which is formed due to overlapping will be _____________
a) In the same direction in which orbitals are concentrated
b) In the opposite direction in which orbitals are concentrated
c) Perpendicular to the direction in which orbitals are concentrated
d) None of the mentioned
Answer: a
Clarification: The direction of the bond formed will be in that direction in which the orbitals are concentrated. For Example: When two p_x orbitals overlap, the bond is formed along the x-axis.

7. Which orbital would form a more stronger bond if both of them have identical stability?
a) The one which is less directionally concentrated
b) The one which is more directionally concentrated
c) Both will be equally strong
d) It differs from atom to atom
Answer: b
Clarification: When the two orbitals have identical stability or energy, the one which is more directionally concentrated would form a stronger bond.

8. The formation of odd electron molecules such as H₂⁺, NO, O₃ is also explained in VBT.
a) True
b) False
Answer: b
Clarification: The Valence Bond Theory does not explain the formation of odd electron molecules such as H₂⁺, NO, O₃ etc, where no electron pairing takes place.

Engineering Chemistry Multiple Choice Questions on “Nanotechnology”.

1. Which of the following is an example of top-down approach for the preparation of nanomaterials?
a) Gas phase agglomeration
b) Molecular self-assembly
c) Mechanical grinding
d) Molecular beam epitaxy
Answer: c
Clarification: Mechanical grinding is an example of top-down approach for the preparation of nanomaterials. All the other options are the example of bottom-up approach.

2. Which of the following is an example of bottom-up approach for the preparation of nanomaterials?
a) Etching
b) Dip pen nano-lithography
c) Lithography
d) Erosion
Answer: b
Clarification: Dip pen nanolithography is an example of bottom-down approach for the preparation of nanomaterials. All the other options are the example of top-down approach.

3. The properties like melting point, solubility, color, etc changes on varying the ___________
a) Size
b) Composition
c) Surface properties
d) None of the mentioned
Answer: a
Clarification: The properties like melting point, solubility, color, etc changes on varying the size of the particles. These all are the physical properties and depends upon the physical characteristics of the particle.

4. The properties like dispersibility, conductivity, etc changes on varying the ___________
a) Size
b) Composition
c) Surface properties
d) None of the mentioned
Answer: c
Clarification: The properties like dispersibility, conductivity, etc changes on varying the surface properties of the nanoparticle. These all are the chemical properties and depend upon the surface characteristics of the particle.

5. Quantum confinement results in ___________
a) Energy gap in semiconductor is proportional to the inverse of the square root of the size
b) Energy gap in semiconductor is proportional to the inverse of the size
c) Energy gap in semiconductor is proportional to the square of size
d) Energy gap in semiconductor is proportional to the inverse of the square of size
Answer: d
Clarification: The energy gap in a semiconductor is proportional to the inverse of the square of the size. This effect is a result of quantum confinement.

6. Which of the following is the principal factor which causes the properties of nanomaterials to differ significantly from other materials?
a) Size distribution
b) Specific surface feature
c) Quantum size effects
d) All of the mentioned
Answer: d
Clarification: Size distribution, specific surface feature and quantum size effects are the principal factor which causes the properties of nanomaterials to differ significantly from other materials.

7. Select the incorrect statement from the following options.
a) Self-assembly is a top-down manufacturing technique
b) In self-assembly, weak interactions play very important role
c) Self-assembling molecules adopt an organised structure which is thermodynamically more stable than the single, unassembled components
d) Compared to the isolated components, the self-assembled structure has a higher order
Answer: a
Clarification: Self-assembly is a bottom-down manufacturing technique. All the other options are correct. In self-assembly, weak interactions play very important role, self-assembling molecules adopt an organised structure which is thermodynamically more stable than the single, unassembled components.

8. Which of the following is the application of nanotechnology to food science and technology?
a) Agriculture
b) Food safety and biosecurity
c) Product development
d) All of the mentioned
Answer: d
Clarification: The application of nanotechnology to food science and technology are agriculture, food safety and biosecurity, product development, food processing and ingredient technologies.

9. What are the advantages of nano-composite packages?
a) Lighter and biodegradable
b) Enhanced thermal stability, conductivity and mechanical strength
c) Gas barrier properties
d) All of the mentioned
Answer: d
Clarification: The advantages of nano-composite packages are-Lighter and biodegradable, enhanced thermal stability, conductivity, mechanical strength and gas barrier properties.

10. The efficiency of today’s best solar cell is about ___________
a) 15-20%
b) 40%
c) 50%
d) 75%
Answer: b
Clarification: The efficiency of today’s best solar cells is about 40%. A solar cell or photovoltaic cell is an electrical device that converts the energy of light directly into electricity by the photovoltaic effect.

Engineering Chemistry Multiple Choice Questions on “Origin of Spectrum”.

1. The analysis of electromagnetic radiation scattered, absorbed or emitted by the molecule is called __________
a) Kaleidoscopy
b) Astronomy
c) Spectroscopy
d) Anatomy
Answer: c
Clarification: The analysis of electromagnetic radiation scattered, absorbed or emitted by the molecule is called spectroscopy. Astronomy is the study of celestial objects and processes the physics, chemistry, and evolution of such objects and processes. A kaleidoscope is an optical instrument, typically a cylinder with mirrors containing loose, colored objects such as beads or pebbles and bits of glass. Anatomy is the branch of biology concerned with the study of the structure of organisms and their parts.

2. The energy level with lower energy is called __________
a) Ground state energy level
b) Initial state energy level
c) Excited state energy level
d) All of the mentioned
Answer: a
Clarification: The lower energy level is called the ground state and the higher energy level is called excited state. The excited state of a system (such as an atom, molecule or nucleus) is any quantum state of the system that has higher energy than the ground state.

3. Absorption spectrum results when an electron in an atom undergoes a transition from __________
a) Higher energy level to a lower one
b) Lower energy level to a higher one
c) Intermediate levels
d) All of the mentioned
Answer: b
Clarification: Absorption spectrum results when an electron in an atom undergoes a transition from lower energy level to a higher one.

4. The energy of a photon is given by __________
a) h/ν
b) ν/h
c) 1/hν
d) hν
Answer: d
Clarification: The energy of a photon is given by hν where ν is the frequency and h is plank constant.

5. Select the incorrect statement from the following option.
a) Emission spectrum results when an electron in an atom undergoes a transition from excited state to the ground state
b) In the emission spectrum, transition takes place with the emission of a photon of energy hν
c) In the emission spectrum, transition takes place with the absorption of a photon of energy hν
d) All of the mentioned
Answer: c
Clarification: In the emission spectrum, transition takes place with the emission of a photon of energy hν. All the other options are correct. Emission spectrum results when an electron in an atom undergoes a transition from excited state to the ground state.

6. The spectra can be broadly classified into two categories. They are __________
a) Atomic and molecular spectra
b) Atomic and electronic spectra
c) Molecular and electronic spectra
d) None of the mentioned
Answer: a
Clarification: The spectra can be broadly classified into two categories: atomic and molecular spectra. Atomic spectra are the spectrum of frequencies of electromagnetic radiation emitted or absorbed during transitions of electrons between energy levels within an atom. Molecular spectra arises from the transition of an electron between the molecular energy levels.

7. In atomic spectroscopy, only electronic transitions are involved.
a) True
b) False
Answer: a
Clarification: In atomic spectroscopy, only electronic transitions are involved. It is the spectrum of frequencies of electromagnetic radiation emitted or absorbed during transitions of electrons between energy levels within an atom.

8. Select the correct statement from the following options.
a) Molecular spectra arises from the transition of an electron between the molecular energy levels
b) In molecular transitions, electronic, rotational and vibration transitions occurs
c) Molecular spectra is more complicated than atomic spectra
d) All of the mentioned
Answer: d
Clarification: Molecular spectra arises from the transition of an electron between the molecular energy levels. In molecular transitions, electronic, rotational and vibration transitions occurs and molecular spectra is more complicated than atomic spectra.

9. The necessary condition for absorption spectrum is that __________
a) hν should be greater than the energy difference
b) hν should be smaller than the energy difference
c) hν should be equal to the energy difference
d) none of the mentioned
Answer: c
Clarification: The necessary condition for absorption spectrum is that hν should be equal to the energy difference(ΔE = E_e – E_g).

10. Spectroscopy deals with the transition that a molecule undergoes on the absorption of suitable radiations determined by quantum mechanical selection rules.
a) True
b) False
Answer: a
Clarification: Spectroscopy deals with the transition that a molecule undergoes on the absorption of suitable radiations determined by quantum mechanical selection rules. The spectra can be broadly classified into two categories: atomic and molecular spectra.