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Multiple choice question for engineering

Set 1

1. If the sign of the wave function is unchanged when the orbital is reflected about its centre, the orbital is
a) Gerade
b) Ungerade
c) Gerade as well as Ungerade
d) None of the mentioned

View Answer

Answer: a [Reason:] If the sign of the wave function is unchanged when the orbital is reflected about its center (i.e., x, y and z are replaced by –x, -y and –z), the orbital is gerade.

2. The filling of molecular orbital takes place according to
a) The Aufbau Principle
b) Pauli Exculsion Principle
c) Hund’s rule of maximum multiplicity
d) All of the mentioned

View Answer

Answer: d [Reason:] According to these principles, molecular orbitals are filled in order of increasing energy.Two electrons in the same orbital cannot have same set of all four quantum numbers identical.

3. Bond Order of O2, F2, N2 respectively are
a) +1, +2, +3
b) +2, +3, +1
c) +2, +1, +3
d) +3, +2, +1

View Answer

Answer: c [Reason:] Bond Order=[[No. Of electrons in bonding molecular orbital]-[No. Of electrons in antibonding molecular orbital]]/2.

4. Arrange the following molecules in decreasing bond length.
a) O2 > O2 > O2+ > O22-
b) O22- > O2 > O2 > O2+
c) O22- > O2 > O2+ > O2
d) O2 > O2+ > O22- > O2

View Answer

Answer: b [Reason:] The bond length is inversely proportional to the bond order. Therefore, the correct is: O22- > O2 > O2 > O2+.

5. Arrange the following molecules in the order of increasing stability.
a) N2+ < N2 < N2 < N22-
b) N22- < N2 < N2 < N2+
c) N22- < N2 = N2+ < N2
d) N2 < N2+ = N2 < N22-

View Answer

Answer: c [Reason:] The order of stability is directly proportional to the bond order. Therefore, the correct order of stability is N22- < N2 = N2+ < N2.

6. On the basis of molecular orbital theory, select the most appropriate option.
a) The bond order of O2 is 2.5 and it is paramagnetic
b) The bond order of O2 is 1.5 and it is paramagnetic
c) The bond order of O2 is 2 and it is diamagnetic
d) The bond order of O2 is 2 and it is paramagnetic

View Answer

Answer: d [Reason:] Oxygen is paramagnetic in nature and its bond order is 2. It is an exceptional case.

7. Which of the following molecule does not exist due to its zero bond order?
a) H2+
b) He2+
c) He2
d) H2

View Answer

Answer: c [Reason:] Molecular orbital electronic configuration of He2 molecule = (σ1s)2 (σ*1s)2.. Bond order = 0, so He2 molecule does not exist.

8. The relative energies of molecular orbitals in increasing order have been found to be as follows:
1s) < (σ*1s) < (σ2s) < (σ*2s) <[(π2py)(π2pz)] < (σ 2px) < [(π*2py)(π*2pz)] < (σ*2px)
a) For O2 to Ne2
b) For H2 to N2
c) For H2 to Ne2
d) For N2 to Ne2

View Answer

Answer: b [Reason:] The relative energies of molecular orbitals in increasing order have been found to be (σ1s) < (σ*1s) < (σ2s) < (σ*2s) <[(π2py)(π2pz)] < (σ2px) < [(π*2py)(π*2pz)] < (σ*2px) for H2 to N2 only.

9. According to Molecular Orbital Theory, the shape and size of a molecular orbital depends upon
a) Shape and size of the combining atomic orbitals
b) Numbers of the combining atomic orbitals
c) Orientation of the combining atomic orbitals
d) All of the mentioned

View Answer

Answer: d [Reason:] The shape and size of a molecular orbital depends upon the shape, size, number and orientation of the combining atomic orbitals.

10. Choose the incorrect statement from the following options.
a) In bonding molecular orbital, electron density is low in the region between the nuclei of bonded atoms
b) The energy of antibonding molecular orbital is higher than that of atomic orbitals from which it is formed
c) Every electron in bonding molecular orbital contributes toward stability of the molecule
d) Antibonding takes place when lobes of atomic orbitals have different signs

View Answer

Answer: a [Reason:] In bonding molecular orbital, electron density is high in the region between the nuclei of bonded atoms. All the other options are correct. The energy of antibonding molecular orbital is higher than that of atomic orbitals from which it is formed. Every electron in bonding molecular orbital contributes toward stability of the molecule. Antibonding takes place when lobes of atomic orbitals have different signs.

Set 2

1. The different types of energies associated with a molecule are
a) Electronic energy
b) Vibrational energy
c) Rotational energy
d) All of the mentioned

View Answer

Answer: d [Reason:] The different types of energies associated with a molecule are electronic energy, vibrational energy, rotational energy and translational energy.

2. During the motion, if the centre of gravity of molecule changes, the molecule possess
a) Electronic energy
b) Rotational energy
c) Translational energy
d) Vibrational energy

View Answer

Answer: c [Reason:] During the motion, if the centre of gravity of molecule changes, the molecule possess translational energy. Translational refers to the movement in horizontal or vertical direction.

3. The correct order of different types of energies is
a) Eel >> Evib >> Erot >> E tr
b) Eel >> Erot >> Evib >> E tr
c) Eel >> Evib >> Etr >> E rot
d) Etr >> Evib >> Erot >> E el

View Answer

Answer: a [Reason:] The correct order is: Eel >> Evib >> Erot >> E tr. Electronic enrgy is the highest whereas translational energy is the lowest.

4. The region of electromagnetic spectrum for nuclear magnetic resonance is
a) Microwave
b) Radio frequency
c) Infrared
d) UV-rays

View Answer

Answer: b [Reason:] The region of electromagnetic spectrum for nuclear magnetic resonance is radio frequency.

5. Which of the following is an application of molecular spectroscopy?
a) Structural investigation
b) Basis of understanding of colors
c) Study of energetically excited reaction products
d) All of the mentioned

View Answer

Answer: d [Reason:] The various applications of molecular spectroscopy are- Structural investigation, basis of understanding of colors and study of energetically excited reaction products.

6. Select the correct statement from the following option.
a) Spectroscopic methods require less time and more amount of sample than classical methods
b) Spectroscopic methods require more time and more amount of sample than classical methods
c) Spectroscopic methods require less time and less amount of sample than classical methods
d) Spectroscopic methods require more time and less amount of sample than classical methods

View Answer

Answer: c [Reason:] Spectroscopic methods require less time and less amount of sample than classical methods (1 mg).

7. State true or false. The results obtained by spectroscopic methods are less reliable, less reproducible and incorrect than classical methods.
a) True
b) False

View Answer

Answer: b [Reason:] The results obtained by spectroscopic methods are reliable, reproducible and correct than classical methods.

8. The transition zone for Raman spectra is
a) Between vibrational and rotational levels
b) Between electronic levels
c) Between magnetic levels of nuclei
d) Between magnetic levels of unpaired electrons

View Answer

Answer: a [Reason:] The transition zone for Raman spectra is between vibrational and rotational levels. Raman spectroscopy is a spectroscopic technique used to observe vibrational, rotational, and other low-frequency modes in a system.

9. The criteria for electronic spin resonance is
a) Periodic change in polarisability
b) Spin quantum number of nuclei > 0
c) Presence of unpaired electron in a molecule
d) Presence of chromophore in a molecule

View Answer

Answer: c [Reason:] The criterion for electronic spin resonance is presence of unpaired electron in a molecule. This spectroscopy is a method for studying materials with unpaired electrons.

10. State true or false. Sample recovery is possible after spectroscopic analysis because sample is not chemically affected.
a) True
b) False

View Answer

Answer: a [Reason:] Sample recovery is possible after spectroscopic analysis because sample is not chemically affected.

Set 3

1. Molecularity of a reaction is equal to the total number of
a) Products formed in the elementary step
b) Reactants taking part in elementary step
c) Reactants and products in the elementary step
d) Reactants and products in the final step

View Answer

Answer: b [Reason:] Molecularity of a reaction is equal to the total number of reactants taking part in elementary step. It is defined as the number of molecules or ions that participate in the rate determining step.

2. State true or false. The molecularity of a multi-step reaction does not make any sense.
a) True
b) False

View Answer

Answer: a [Reason:] The molecularity of a multi-step reaction does not make any sense. The molecularity of each step is different. And molecularity of one step can only be determined at a time.

3. The elementary processes with molecularity greater than ________ are not known.
a) 1
b) 2
c) 3
d) 0

View Answer

Answer: c [Reason:] The elementary processes with molecularity greater than three are not known. There is no such reaction which has the molecularity greater than three.

4. Which of the following statement is incorrect about the molecularity of a reaction?
a) It is a theoretical concept
b) Each step of a multi-step reaction has a unique molecularity
c) It is equal to the total number of reactants taking part in elementary step
d) It can be zero, fractional or integer

View Answer

Answer: d [Reason:] Molecularity is always a whole number. It can be neither zero nor fractional. All the other options are correct.

5. Which of the following factor does not effect the rate of reaction?
a) Concentration of the reactant
b) Temperature
c) Pressure
d) Effect of catalyst

View Answer

Answer: c [Reason:] The reaction rate does not depend upon the pressure. It only depends upon the concentration of the reactant, temperature and effect of catalyst.

6. The effective collisions between the reactant molecules at higher temperatures
a) Increase
b) Decrease
c) Remains same
d) First increase then decrease

View Answer

Answer: a [Reason:] The effective collisions between the reactant molecules at higher temperatures increase. At higher temperature randomness increases and molecules moves with faster velocity which results in more collision between the reactants.

7. Concentration of the reactants is __________ proportional to the number of collisions and _________ proportional to the reaction rate.
a) Directly, inversely
b) Directly, directly
c) Inversely, directly
d) Inversely, inversely

View Answer

Answer: b [Reason:] Concentration of the reactants is directly proportional to the number of collisions and also directly proportional to the reaction rate. The more the collision, more will be the reaction rate and hence more will be the concentration of reactants.

8. The reaction rate is greatly influenced by
a) Nature of bond in the reactant molecules
b) Strength of bond in the reactant molecules
c) Both nature and strength of the reactant molecules
d) It does not depend on either nature or strength of the reactant molecules

View Answer

Answer: c [Reason:] The reaction rate is greatly influenced by both nature and strength of the reactant molecules. Reactants are the major factor that effects the rate of the reaction.

9. State true or false. The reactions register an increase in rates in the presence of radiations of specific wavelengths.
a) True
b) False

View Answer

Answer: a [Reason:] The reactions register an increase in rates in the presence of radiations of specific wavelengths.

10. Select the correct option from the following option.
a) Catalyst is used to increase the rate of reaction by altering chemically during the course of reaction.
b) Catalyst is used to decrease the rate of reaction by altering chemically during the course of reaction.
c) Catalyst is used to increase the rate of reaction and remains unaltered chemically during the course of reaction.
d) Catalyst is used to decrease the rate of reaction and remains altered chemically during the course of reaction.

View Answer

Answer: c [Reason:] Catalyst is used to increase the rate of reaction and remains unaltered chemically during the course of reaction. With a catalyst, reactions occur faster and require less activation energy. Because catalysts are not consumed in the catalyzed reaction, they can continue to catalyze the reaction of further quantities of reactant.

Set 4

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

View Answer

Answer: c [Reason:] 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

View Answer

Answer: b [Reason:] 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

View Answer

Answer: a [Reason:] 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

View Answer

Answer: c [Reason:] The properties like dispersibility, conductivity, etc changes on varying the surface properties of the nanoparticle. These all are the chemical properties and depends 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 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

View Answer

Answer: d [Reason:] The energy gap in a semiconductor is proportional to the inverse of the square of 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 the mentioned

View Answer

Answer: d [Reason:] 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 a 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

View Answer

Answer: a [Reason:] 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 a 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

View Answer

Answer: d [Reason:] 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

View Answer

Answer: d [Reason:] 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%

View Answer

Answer: b [Reason:] 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.

Set 5

1. The nuclei with spin quantum number greater than _______ can exhibit the NMR phenomenon.
a) 0
b) 5
c) 10
d) -5

View Answer

Answer: a [Reason:] The nuclei with spin quantum number greater than zero can exhibit the NMR phenomenon. Nuclear magnetic resonance spectroscopy, NMR spectroscopy, is a research technique that exploits the magnetic properties of certain atomic nuclei.

2. The number of different orientations which a magnetic nucleus can take is
a) 2I
b) 2I-1
c) 2I+1
d) 4I

View Answer

Answer: c [Reason:] The number of different orientations which a magnetic nucleus can take is 2I+1.

3. Number of NMR signals obtained in CH3COCH3 will be
a) 6
b) 3
c) 2
d) 1

View Answer

Answer: d [Reason:] Number of NMR signals obtained in CH3COCH3 will be 1. Nuclear magnetic resonance spectroscopy, is a research technique that exploits the magnetic properties of certain atomic nuclei.

4. State true or false. Propene as well as 2-Butene(cis) will show equal number of signals in their NMR spectra.
a) True
b) False

View Answer

Answer: b [Reason:] Propene as well as 2-Butene(cis) will not show equal number of signals in their NMR spectra.

5. Select the incorrect statement from the following option.
a) TMS stands for tetra methyl silane
b) All the hydrogen in TMS have the same chemical shift
c) TMS has a high boiling point, so it is not easily lost when holding the NMR sample
d) TMS is relatively unreactive with most functional groups

View Answer

Answer: c [Reason:] TMS has a low boiling point so it can be easily removed from recoverable sample of an organic compound. All the other options are correct. TMS is relatively unreactive with most functional groups.

6. The NMR spectra of the functional isomers of the molecular formula C2H6O show _________ and _________ signals respectively.
a) 1, 2
b) 1, 3
c) 1, 4
d) 1, 5

View Answer

Answer: b [Reason:] The NMR spectra of the functional isomers of the molecular formula C2H6O show one and three signals respectively.

7. The number of signals in 1-propanol are _________ while those in 2-propanol are ______
a) 4, 3
b) 4, 2
c) 2, 4
d) 3, 4

View Answer

Answer: a [Reason:] The number of signals in 1-propanol are 4 while those in 2-propanol are 3.

8. State true or false. For NMR spectrum, carbon tetrachloride and water can be successfully used as solvent.
a) True
b) False

View Answer

Answer: a [Reason:] For NMR spectrum, carbon tetra-chloride and water can be successfully used as solvent. NMR is routinely used in advanced medical imaging techniques, such as in magnetic resonance imaging (MRI).

9. In how many ways –CH3 protons can couple with the protons on adjacent carbon atom relative to the external field.
a) 1
b) 2
c) 3
d) 4

View Answer

Answer: d [Reason:] In four ways –CH3 protons can couple with the protons on adjacent carbon atom relative to the external field.

10. Which of the following is inversely proportional to the chemical shifts positions (δ)?
a) Frequency of unknown group of protons
b) Frequency of TMS
c) Operating frequency of the instrument
d) All of the mentioned

View Answer

Answer: c [Reason:] Operating frequency of the instrument is inversely propotional to the chemical shifts positions (δ).