Category: Class 11 Chemistry Objective Questions

Chemistry Multiple Choice Questions on “Classification of Organic Compounds”.

1. What is the other name for acyclic compounds?
a) Aliphatic
b) Aromatic
c) Heterocyclic
d) Alicyclic
Answer: a
Clarification: Acyclic or open chain compounds are also called as aliphatic compounds as they consist of straight or branched chain compounds. Aromatic, heterocyclic and alicyclic compounds are closed chain or ring compounds.

2. The successive members of a homologous series differ by an unit of which of the following?
a) –CH₃
b) CH₃CH₃
c) –CH₂
d) –CH₂CH₃
Answer: c
Clarification: The successive members of a homologous series differ by a CH₂ unit. Taking, methanol (CH₃OH), ethanol (CH₃CH₂OH), and propanol (CH₃CH₂CH₂OH) as examples. From this, we clearly understand that as the series progresses, the difference between each successive member is a CH₂ unit.

3. Tropolone is a benzenoid compound.
a) True
b) False
Answer: b
Clarification: Tropolone is a non-benzenoid compound. It does not have a benzene ring and hence, not a benzenoid compound. Benzenoid compounds are the compounds that include benzene rings. For example: Benzene, Aniline, Naphthalene, etc.

4. Which of these is not an aliphatic compound?
a) Acetic acid
b) Acetaldehyde
c) Ethane
d) Tetrahydrofuran
Answer: d
Clarification: Tetrahydrofuran is a closed chain or a ring compound. Acetic acid, acetaldehyde, and ethane are open chain compounds, thereby, making them aliphatic compounds. Tetrahydrofuran is an organic compound with the formula (CH₂)₄O.

5. Pick out the option that is not a functional group from the following.
a) Hydroxyl group
b) Benzene group
c) Aldehyde group
d) Carboxylic acid group
Answer: b
Clarification: Benzene group is not a functional group. Functional groups can be defined as an atom or group of atoms joined in a specified manner which is responsible for the characteristic chemical properties of the organic compound. Hydroxyl group (-OH), aldehyde group (-CHO), and carboxylic acid group (-COOH), all cause changes in chemical properties when attached to the hydrocarbon chains.

Chemistry Multiple Choice Questions on “Green Chemistry”.

1. Which of the following is a greener route to produce ethanal commercially?
a) Catalytic cracking of ethanol
b) Oxidation of ethene with an ionic catalyst
c) Steam reforming of methanol
d) Dehydrogenation of ethylene
Answer: b
Clarification: Ethanal can be prepared by oxidation of ethene, in the presence of an ionic catalyst in an aqueous medium. This is a greener method and gives 90% of yield.

2. Name the conventional solvent that was used for dry cleaning purposes which later confirmed to be a suspected carcinogen.
a) Supercritical CO₂
b) Phenanthrene
c) Tetrachloroethene
d) Benzene aldehyde
Answer: c
Clarification: Tetrachloroethene was used as a solvent for dry cleaning purposes. It is a suspected carcinogen and groundwater contaminant. It is replaced by greener solvent like supercritical CO₂.

3. Which of the following is not a principle of Green Chemistry?
a) Green solvents and auxiliaries
b) Use of renewable feedstock
c) Hazardous chemical synthesis
d) Design for energy efficiency
Answer: c
Clarification: Synthetic methods should avoid using or generating substances toxic to humans and/or the environment. Hence less hazardous chemical synthesis is an important principle.

4. Green chemistry is the design of chemical products and processes that reduce or eliminate the use and generation of hazardous substances. Identify the technique used in this area.
a) Bioamplification
b) Polymer manufacturing
c) Pesticide synthesis
d) Use of sunlight and Microwave-assisted reaction
Answer: d
Clarification: Photochemical reaction occurs when light energy gets absorbed by a substances’ molecule. It is a green route as no byproduct will be formed. Vitamin D3 synthesis is assisted by a photochemical reaction.

5. Which of the following gas was traditionally used to bleach paper?
a) Sulfur
b) Carbon dioxide
c) Chlorine
d) Fluorine
Answer: c
Clarification: Chlorine gas was used to bleach paper. It has good oxidizing properties. Nowadays H₂O₂ with a suitable catalyst is used for bleaching purposes as it does not contaminate groundwater.

6. Replacement of liquid CO₂ by halogenated solvent will result in less harm to groundwater.
a) True
b) False
Answer: b
Clarification: Halogenated solvents contaminate groundwater. Whereas liquified CO₂ leaves a lower amount of residue. It is also a non-toxic and attractive solvent for temperature-sensitive materials.

7. Which of the following is a green solvent used for bleaching clothes?
a) Hydrogen peroxide
b) Tetrachloroethene
c) Benzene
d) Toluene
Answer: a
Clarification: Hydrogen peroxide can easily breakdown into water and oxygen. It is a good oxidizing agent and a strong bleaching agent. Use of H₂O₂ gives better results and makes use of a lesser amount of water.

8. Identify the non-toxic and green solvent.
a) Liquified carbondioxide
b) Benzene
c) Carbon tetrachloride
d) Toluene
Answer: a
Clarification: When compared to conventional solvents, liquified CO₂ leaves a lower amount of residue. It is also a non-toxic and attractive solvent for temperature-sensitive materials.

Chemistry Multiple Choice Questions on “Quantum Mechanical Model of Atom”.

1. The principal quantum number describes ____
a) energy and size of the orbit
b) the shape of the orbital
c) spatial orientation of the orbital
d) the spin of the electron
Answer: a
Clarification: Among the four quantum numbers, the principal quantum number describes the size and energy of the orbit. It is represented by the symbol “n”. For shells, K, L, M, N and O, n is given by 1, 2, 3, 4 and 5.

2. What is the shape the orbital, whose “l” is 1?
a) Spherical
b) Dumbbell
c) Double dumbbell
d) Complex
Answer: b
Clarification: The azimuthal quantum number is given by “l”. When l = 0, 1, 2 and 3, they are s-orbital, p-orbital, d-orbital and f-orbital respectively. The shapes of s-orbital, p-orbital, d-orbital, and f-orbital are Spherical, Dumbbell, Double dumbbell and Complex respectively.

3. What is the magnetic quantum number of the orbital 2p_z?
a) 1
b) ±1
c) -1
d) 0
Answer: d
Clarification: The magnetic quantum of an orbital range from -( l – 1) to l – 1. Its symbol is given by m. For 2p orbital, there are 3 magnetic quantum numbers namely -1, 0 and 1. For 2p_z orbital its 0, taken that z is the internuclear axis.

4. Total number of nodes for 3d orbital is ________
a) 3
b) 2
c) 1
d) 0
Answer: b
Clarification: Total number of nodes include angular and radial nodes. Angular nodes and radial nodes are given by the formula n – l -1 and l respectively. So the total number of nodes are n – l -1 + l = n – 1. For 3d orbit, “n” is 3, so total number nodes is 3 – 1 = 2.

5. Which of the following set of quantum numbers is not valid?
a) n = 5, l = 2, m = 0, s = 1/2
b) n = 1, l = 2, m = 0, s = 1/2
c) n = 5, l = 3, m = 2, s = 1/2
d) n = 5, l = 2, m = 0, s = -1/2
Answer: b
Clarification: The set of quantum number n = 1, l = 2, m = 0, s = 1/2, is not valid because the value of azimuthal quantum number should lie only in between 0 and n-1, where n is principal quantum number. So the above set of quantum numbers is not valid.

6. According to the Aufbau’s principle, which of the following orbital should be filled first?
a) 5d
b) 4p
c) 3p
d) 2s
Answer: d
Clarification: As per the Aufbau’s principle, the orbital or subshell with the lowest energy should be filled first. The ascending order of orbital’s energy is given by 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 4f, 5d, 6p, 7s. So 2s orbital should be filled first.

7. No two electrons have the same set of all four quantum numbers.
a) True
b) False
Answer: a
Clarification: Yes, no two electrons have the same set of all four quantum numbers. This is explained by Pauli’s exclusive principle. At most electrons can have all 3 quantum numbers the same as they are in the same orbital. But the spin quantum number’s values are different.

8. The below process of filling electrons in an orbital follows __________

a) Aufbau principle
b) Hund’s rule of maximum multiplicity
c) Pauli’s exclusive principle
d) Electronic configuration
Answer: b
Clarification: According to Hund’s rule of maximum multiplicity, the pairing of electrons cannot be started until each of the orbitals is singly occupied. The reason behind this is that the half-filled or fully filled orbitals are much more stable comparatively.

9. How many electrons can exist with the principal quantum number’s value as 4?
a) 16
b) 4
c) 32
d) 12
Answer: c
Clarification: The number of orbitals within an orbit is n2. But as each orbital can accommodate 2 electrons, the number of electrons that can exist with the “n” as the principal quantum number is 2n². So here 2n² = 2(4)² = 2(16) = 32.

10. Write the values for l, n, and m for Ψ_3,1,0?
a) 1, 3, 0
b) 3, 1, 0
c) 0, 3, 1
d) 1, 0, 3
Answer: a
Clarification: The representation of the Schrodinger wave function is given by Ψ_n,l,m. Therefore by comparing Ψ_n,l,m and Ψ_3,1,0 we get that n = 3, l = 1 and m = 0. Here n, l, and m are principal, azimuthal and magnetic quantum numbers respectively.

Chemistry Multiple Choice Questions on “States of Matter – Intermolecular Forces”.

1. What are the forces of attraction and repulsion between interacting molecules known as _________
a) attractive forces
b) repulsive forces
c) intermolecular forces
d) intramolecular forces
Answer: c
Clarification: Intermolecular means between molecules and intramolecular means within in molecule. Both attractive and repulsive forces include intermolecular forces. Therefore, the forces of attraction and repulsion between interacting molecules are known as Intermolecular forces.

2. Deviation of real gas behavior from ideal gas is discovered by _____________
a) Jonathan
b) Van der Waals
c) Boyle
d) Newland
Answer: b
Clarification: A Dutch scientist named Johannes van der Waals found out the reason for real gas behavior’s deviation from ideal gas behavior. And he said that those forces which were named van der Waals were responsible.

3. London force is also known as _____________
a) dispersion force
b) van der Waals forces
c) hydrogen bonding
d) covalent bonds
Answer: a
Clarification: Electrically symmetrical atoms and non-polar molecules having zero dipole movement due to their electron distribution may sometimes develop a momentary dipole also known as London force or the Dispersion forces.

4. Dispersion force’s interaction energy is proportional to (take “r” as the distance between the two particles) ___________
a) r⁶
b) 1/r^-6
c) r²
d) 1/r⁶
Answer: d
Clarification: The interaction energy between two atoms or molecules experiencing dispersion or London forces is inversely proportional to the sixth power of the distance between those molecules when found, experimentally.

5. Dipole-Dipole forces are stronger than _______ and weaker than _________ interactions.
a) dipole-induced dipole, london
b) ion-ion, dispersion
c) ion-ion, london
d) london, ion-ion
Answer: d
Clarification: Dipole-Dipole forces are stronger than London forces and weaker than ion-interactions. As only the partial charges are involved. London forces have no charges, and ion-ion forces have full charges.

6. HCl is an example of __________
a) dipole-dipole intercations
b) dipole-induced dipole interactions
c) london intercation
d) van der waals interaction
Answer: a
Clarification: Dipole-Dipole interactions occur between molecules having permanent dipoles. And also the ends of dipoles posses partial charge which represented by a Greek letter δ. In an HCl molecule, the same type of interactions occur.

7. Take “r” as the distance between two molecules. The energy between stationary polar molecules is proportional to ____________ in the case of dipole-dipole intercations.
a) 1/r³
b) r³
c) r²
d) 1/r²
Answer: a
Clarification: The energy between two polar molecules which are stationary, is inversely proportional to the cube of the distance between the molecules, in the case of dipole-dipole intercations. This interaction is stronger than the London forces.

8. Which of the following interaction occurs between a permanent dipole and a neutral molecule?
a) Dipole-Dipole interactions
b) Dipole-induced dipole interactions
c) London interaction
d) Van der Waals interaction
Answer: b
Clarification: Dipole-induced dipole interactions occur between a molecule of permanent dipole and molecule lacking permanent dipole. The dipole gets induced to the other molecule in this particular interaction.

9. Hydrogen bond plays a vital role in determining substance properties and structure. Which of the following may not an example?
a) Proteins
b) Nucleic acids
c) Methane molecule
d) Water
Answer: c
Clarification: As per the above statement, substance properties and structure is determined as per the hydrogen bond present in them, but in a methane molecule, there is no hydrogen bond. So it may not be an example.

10. Molecules do exert repulsive forces on one other.
a) True
b) False
Answer: a
Clarification: When two molecules come closer, the electron clouds between them they repel. This is the reason why solids and liquids cannot be easily compressed. As the distance between molecules decreases, the repulsive forces become much stronger.

Chemistry Multiple Choice Questions & Answers (MCQs) on “States of Matter – Liquefaction of Gases”.

1. Which of The following is a critical temperature for Carbon dioxide?
a) 32-degree centigrade
b) 30.98-degree centigrade
c) 40-degree centigrade
d) 30.91 degree Kelvin
Answer: b
Clarification: The critical temperature of carbon dioxide is a maximum temperature where the carbon dioxide can remain as a liquid below this temperature. The carbon dioxide is gas so the critical temperature for Carbon dioxide is 30.98 degrees centigrade.

2. Which of the following is Greater?
a) Boyle’s temperature
b) Boyle’s temperature = critical temperature
c) Critical temperature
d) Boyle’s temperature = 1/critical temperature
Answer: a
Clarification: Boyle’s temperature T_B is given by a/Rb critical temperature T_C is given by 8a/27Rb, where a is the pressure correction term and b is a volume correction term as per van der Waal’s equation. So Boyle’s temperature is greater than the critical temperature.

3. What is the ratio of critical temperature to Boyle’s temperature of the same gas?
a) 8/27
b) 27/8
c) 8
d) 27
Answer: a
Clarification: The maximum temperature gas can remain liquid is known as critical temperature. The temperature till which a gas behaves like an ideal gas is Boyle’s temperature. Boyle’s temperature T_B is given by a/Rb critical temperature T_c is given by 8a/27Rb. So the ratio is 8/27.

4. A fluid is a _______________
a) gas
b) liquid
c) solid
d) both gas and liquid
Answer: d
Clarification: A fluid is a gas or liquid that can be used to recognize the continuity. The fluid is something deforms under shear stress application and flows from one place to another, it is also a subset of States of matter.

5. A gas that is liquefied by applying pressure below critical temperature is called ____________ of the substance.
a) vapor
b) liquid
c) solid
d) plasma
Answer: a
Clarification: At critical temperature liquid state changes into gaseous state continuously the surface that separates both this state disappears and gas below critical temperature can be liquefied by applying pressure and this is called vapor of the substance.

6. If the value of a is greater, what does it mean?
a) the gas liquefies easily
b) the gas cannot liquify easily
c) gas obeys ideal gas law
d) gas particles have random motion
Answer: a
Clarification: The value of an in van der Waals equation is a measure of the magnitude of intermolecular attractive forces within a gas. It is independent of temperature and pressure. As attractive forces are more, the gas can be liquefied easily.

7. Which of the following can be the value of “b” for Helium?
a) 23.71 x 10^-6 m²/mol
b) 23.71 x 10^-6 m³/mol
c) 23.71 x 10^-6 m³ mol
d) 23.71 x 10^-6 m/mol
Answer: b
Clarification: From van der Waal’s equation (P – an²/V²)(V – nb) = nRT, we have that units of volume and number of moles x b are same. So L = mol x b; units of b is L/mol otherwise can be written as m³/mol.

8. The value of b for carbon dioxide is given as 42.69 x 10^-6m³/mol. What do you think is the volume of a molecule?
a) 7.59 m³
b) 7.03 m³
c) 76.09 m³
d) 7.09 m³
Answer:d
Clarification: From van der Waal’s equation (P – an²/V²)(V – nb) = nRT, we know that V = b/NA = 42.69 x 10^-6m³/mol/6.023 x 1023 molecules/mol. That equals 7.09 m³/molecule. So the volume of a molecule is 7.09m³.

9. In van der Waal’s equation, b is known as ______________
a) volume constant
b) pressure constant
c) volume correction
d) pressure correction
Answer: c
Clarification: In the van der Waal’s equation (P – an²/V²)(V – nb) = nRT, b is the volume correction term and is 4 times as the volume of a molecule. The letter a is the pressure correction term in the van der Waal’s equation.

10. Which of the following is an expression for Boyle’s temperature?
a) a/Rb
b) 27a/R
c) a/b
d) Ra/8b
Answer: a
Clarification: Boyle’s temperature T_b is given a/Rb, where a and b are the van der Waal’s constants for pressure and volume correction. The temperature till which a gas behaves like an ideal gas is Boyle’s temperature.

Chemistry Question Bank for Class 11 on “Ionic Equilibrium in Solution”.

1. CH₃COOH (rightleftharpoons) CH₃COO^– + H⁺ is in __________________
a) ionic equilibrium
b) chemical equilibrium
c) dynamic equilibrium
d) physical equilibrium
Answer: a
Clarification: The equilibrium that is attained between the ionized molecules and the ions in the solution of weak electrolyte is called Ionic Equilibrium. CH₃COOH (rightleftharpoons) CH₃COO^– + H⁺ is an example; CH₃COO^– and H⁺ are ions.

2. Electrolytes conduct electricity.
a) True
b) False
Answer: a
Clarification: Chemical substances which can conduct electricity in their Aqua state or in the molten state are called electrolytes. The conduction of current through the electrolyte is due to the movement of Ions, hence the above statement is true.

3. Which of the following may not be a strong electrolyte?
a) hydrochloric acid
b) sulfuric acid
c) nitric acid
d) ammonia
Answer: d
Clarification: Electrolytes which dissociate almost completely into constituent ions in aqueous solutions are known as strong electrolytes. Therefore ammonia is not a strong electrolyte because it can’t dissociate completely.

4. All organic acids except sulfonic acid are _____________ electrolytes.
a) weak
b) strong
c) not
d) neither strong nor weak
Answer: a
Clarification: Electrolytes which dissociate into a lesser extent in aqua solution are called weak electrolytes. All organic acids except sulfonic acids and bases like Ammonia, Ammonium hydroxide, amines, etc are weak electrolytes.

5. Can nonelectrolytes conduct electricity?
a) yes
b) no
c) sometimes
d) cannot say
Answer: b
Clarification: Michael Faraday classified substances into two categories; one is electrolytes and nonelectrolytes, nonelectrolytes do not dissociate into ions in a solution. So they do not conduct electricity.

6. Sugar solution __________ electricity.
a) do not conduct
b) conducts
c) depends on the type of sugar
d) cannot say
Answer: a
Clarification: Aqueous solution of sugar does not conduct electricity, but Aqueous solution of sugar conducts electricity. This is because the aqueous solution of sugar is a nonelectrolyte, whereas the salt solution is an electrolyte.

7. Which of the following is in Ionic Equilibrium?
a) 2AgI + Na₂S (rightleftharpoons)Ag₂S + 2NaI
b) 4 NH₃ + 5 O₂ (rightleftharpoons)4 NO + 6 H₂O
c) TiCl₄ + 2 H₂O (rightleftharpoons)TiO₂ + 4 HCl
d) H₂O + H₂O (rightleftharpoons)H₃O⁺ + OH^–
Answer: d
Clarification: Only H₂O + H₂O (rightleftharpoons)H₃O⁺ + OH^– is in ionic equilibrium. As the equilibrium established between the unionized molecules and the ions in the solution of weak electrolytes is known as Ionic Equilibrium.

8. What is the degree of dissociation for strong electrolytes?
a) 1
b) 0
c) less than 1
d) greater than 1
Answer: a
Clarification: Degree of dissociation is the fraction of the total number of molecules which dissociate into constituent ions, it is represented by the symbol ɑ. As a strong electrolyte dissociate completely, it values is 1.

9. Degree of dissociation does not depend on which of the following factors?
a) nature of the solute
b) nature of the solvent
c) sound
d) concentration
Answer: c
Clarification: Values of the degree of dissociation or degree of ionization depends upon the following factors: 1) the nature of the solute, 2) the nature of the solvent 3) concentration and 4) temperature of the solution.

10. K in K = Cα²/1 – ɑ represents ___________
a) dissociation constant
b) molar concentration
c) degree of dissociation degree of ionization
d) degree of ionization
Answer: a
Clarification: The above equation represents Ostwald’s dilution law, where K is the dissociation constant, C is the molar concentration of the solution and ɑ is a degree of dissociation or degree of ionization of the solution.

To practice Chemistry Question Bank for Class 11,