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MDCAT
Chemistry
2023

Chemistry · Hydrocarbons

Work through this past-paper style MCQ, then read the full explanation. Practice more chemistry questions on mMCQ with adaptive practice and topic analytics.

Question

In following molecules which one has the shortest C-C bond length?

Options
  • A

    C3H8

  • B

    C2H6

  • C

    C2H4

  • D

    C2H2

Explanation

The bond lengths in the given molecules are:


- C3H8 (propane): 1.54 Å (single bond)

- C2H6 (ethane): 1.53 Å (single bond)

- C2H4 (ethylene): 1.33 Å (double bond)

- C2H2 (acetylene): 1.20 Å (triple bond)


The shortest C-C bond length is found in acetylene (C2H2), which has a triple bond between the two carbon atoms. This is because triple bonds are shorter than double bonds, which are shorter than single bonds.

C3H8 (propane): has single bonds, which are longer than triple bonds.

C2H6 (ethane): has single bonds, which are longer than triple bonds.

C2H4 (ethylene): has a double bond, which is longer than a triple bond

The bond lengths in the given molecules are:


- C3H8 (propane): 1.54 Å (single bond)

- C2H6 (ethane): 1.53 Å (single bond)

- C2H4 (ethylene): 1.33 Å (double bond)

- C2H2 (acetylene): 1.20 Å (triple bond)


The shortest C-C bond length is found in acetylene (C2H2), which has a triple bond between the two carbon atoms. This is because triple bonds are shorter than double bonds, which are shorter than single bonds.

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Tagged under Chemistry · Hydrocarbons · 2023