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NEET CHEMISTRYOrganic Chemistry – Some Basic Principles and Techniques Medium

Question

Which of the following is not a correct statement?

A

The electron-deficient molecules can act as Lewis acids

B

The canonical structures have no real existence

C

Every AB5\text{AB}_5 molecule does, in fact, have square pyramid structure

D

Multiple bonds are always shorter than corresponding single bonds

Step-by-Step Solution

According to VSEPR theory, a molecule of the type AB5\text{AB}_5 (where the central atom 'A' has 5 bond pairs and 0 lone pairs) has a trigonal bipyramidal geometry (e.g., PCl5\text{PCl}_5) . A square pyramidal geometry is observed in molecules of the type AB5E\text{AB}_5\text{E}, where the central atom has 5 bond pairs and 1 lone pair (e.g., BrF5\text{BrF}_5) . Therefore, the statement that every AB5\text{AB}_5 molecule has a square pyramidal structure is incorrect. The other statements are true: electron-deficient species act as Lewis acids , canonical (resonance) structures are hypothetical and have no real existence , and multiple bonds (double/triple) are shorter than their corresponding single bonds .

Exam Context & Concepts Covered

This question aligns with the NEET CHEMISTRY syllabus, specifically targeting concepts from Organic Chemistry – Some Basic Principles and Techniques . Mastering this topic is crucial for scoring well in the upcoming medical entrance examinations. Solving conceptually related problems will help you understand the nuances of these concepts and improve your problem-solving speed.

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Which one of the following pairs is isostructural (i.e., having the same shape and hybridization)?

A.$\text{BCl}_3$ and $\text{BrCl}_3$
B.$\text{NH}_3$ and $\text{NO}_3^-$
C.$\text{NF}_3$ and $\text{BF}_3$
D.$\text{BF}_4^-$ and $\text{NH}_4^+$
MediumSolve

Among the following, isoelectronic species are:

A.$CO_{2}, NO_{2}$
B.$NO_{2}^{-}, CO_{2}$
C.$CN^{-}, CO$
D.$SO_{2}, CO_{2}$
EasySolve

Which one of the following pairs of species have the same bond order?

A.$\text{CO}$, $\text{NO}$
B.$\text{O}_2^-$, $\text{CN}^-$
C.$\text{CN}^-$, $\text{NO}^+$
D.$\text{N}^+$, $\text{CN}^+$
MediumSolve

In a regular octahedral molecule, $MX_{6}$, the number of $X–M–X$ bonds at 180º is:

A.Two
B.Six
C.Four
D.Three
EasySolve

Which of the following pairs of ions are isoelectronic and isostructural?

A.CO₃²⁻, SO₃²⁻
B.ClO₃⁻, CO₃²⁻
C.SO₃²⁻, NO₃⁻
D.ClO₃⁻, SO₃²⁻
MediumSolve

Which orbital does the additional electron occupy when $O_{2}$ is converted to the $O_{2}^{-}$ ion?

A.$\pi$ orbital
B.$\sigma^{*}$ orbital
C.$\sigma$ orbital
D.$\pi^{*}$ orbital
MediumSolve

A species that does not exhibit paramagnetism is:

A.$N_{2}^{+}$
B.$O_{2}^{-}$
C.$CO$
D.$NO$
MediumSolve

The total number of $\pi$-bond electrons in the following structure is:

A.4
B.8
C.12
D.16
EasySolve

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