Sigma and Pi Bonds

Sigma and Pi Bonds MDCAT MCQs with answers

12 past paper MCQs on Sigma and Pi Bonds, from the Chemical Bonding unit of MDCAT Chemistry. The year each question appeared is shown where known; tap “Show answer” for the correct option and a short solution.

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1.In propene pi-bond is formed by sideway overlap of: (UHS MDCAT 2025)

  1. s-orbitals
  2. p-orbitals
  3. sp2 hybrid orbitals
  4. sp3 hybrid orbitals
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Correct answer: (b) p-orbitals

A pi bond is the sideways overlap of two unhybridized p orbitals.

2.The theories which explain the formation of sigma and pi bond are EXCEPT: (UHS MDCAT 2025)

  1. MOT
  2. VBT
  3. VSEPR
  4. CFT
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Correct answer: (c) VSEPR

VSEPR predicts shape from electron pair repulsion; it says nothing about how a bond is formed.

3.Bond order is equal to: (NUMS MDCAT 2025)

  1. Difference between number of bonding electrons and antibonding electrons
  2. The sum of number of bonding electrons and antibonding electrons
  3. Half of the difference between number of bonding electrons and antibonding electrons
  4. Quarter of the difference between number of bonding electrons and antibonding electrons
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Correct answer: (c) Half of the difference between number of bonding electrons and antibonding electrons

Bond order is half the difference between the bonding and the antibonding electrons.

4.How many sigma and pi bonds are present in maleic anhydride? (SZABMU MDCAT 2025)

  1. 5 sigma 3 pi
  2. 6 sigma 3 pi
  3. 7 sigma 2 pi
  4. 9 sigma 3 pi
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Correct answer: (d) 9 sigma 3 pi

Maleic anhydride has nine sigma bonds and three pi bonds, two of them in the carbonyl groups.

5.Which of the following has a coordinate bond? (UHS MDCAT 2024)

  1. NaCl
  2. CaO
  3. NH3BF3
  4. H2O
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Correct answer: (c) NH3BF3

Nitrogen gives both electrons of the bond to the empty orbital of boron.

6.Q.96 Why dimer of Aluminum chloride is formed (UHS MDCAT 2023)

  1. Aluminum is electron rich
  2. Aluminum is having lone pair of electron
  3. Aluminum donates lone pair to form bridge
  4. Aluminum forms coordinate bonds with chlorine to complete its octet
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Correct answer: (d) Aluminum forms coordinate bonds with chlorine to complete its octet

Aluminium is two electrons short of an octet, so a chlorine of the other molecule donates a pair as a bridge.

7.The pi bonds surrounding the sigma bonds in an ethyne molecule are in the shape of: (PMC MDCAT 2022)

  1. Linear
  2. Cylindrical
  3. Trigonal Planar
  4. Tetrahedral
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Correct answer: (b) Cylindrical

The two pi bonds of ethyne at right angles make a cylinder of charge round the axis.

8.Pi (π) bond between two atoms is (PMC MDCAT 2022)

  1. Formed by axial overlapping of atomic orbitals, and is stronger than sigma bond.
  2. Formed by parallel overlapping of atomic orbitals, and is stronger than sigma bond.
  3. Formed by axial overlapping of atomic orbitals, and is weaker than sigma bond.
  4. Formed by parallel overlapping of atomic orbitals, and is weaker than sigma bond.
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Correct answer: (d) Formed by parallel overlapping of atomic orbitals, and is weaker than sigma bond.

A pi bond is the sideways overlap of two p orbitals, and that overlap is poorer than the head-on one of a sigma bond.

9.Which of the following orbitals has lower energy? (PMC MDCAT 2022)

  1. Anti-bonding molecular orbital
  2. Anti-bonding atomic orbitals
  3. Bonding half-filled orbitals
  4. Bonding molecular orbital
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Correct answer: (d) Bonding molecular orbital

The bonding molecular orbital lies below the atomic orbitals it was made from.

10.Which of the following molecules has the largest number of shared pairs of electrons? (UHS MDCAT 2018)

  1. C2H4
  2. N2
  3. CO2
  4. NH3
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Correct answer: (a) C2H4

Ethene has four carbon hydrogen bonds and a double bond between the carbons, six shared pairs in all.

11.How many pi bond(s) are there in ethene? (UHS MDCAT 2017)

  1. None
  2. One
  3. Two
  4. Three
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Correct answer: (b) One

The double bond of ethene is one sigma and one pi bond.

12.Pi-bond is formed by sideways overlap of _________? (UHS MDCAT 2017)

  1. s-orbitals
  2. p-orbitals
  3. d-orbitals
  4. None of the given options
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Correct answer: (b) p-orbitals

A pi bond is the sideways overlap of two p orbitals.

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