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Chemical Bonding and Molecular Structure · Question 62

AIPMT 2011 (Mains)MCQMedium📈 Topic in 25% papers+4−1
1

Which of the following structures is the most preferred and hence of lowest energy for SO3?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]

Answer

(4) [figure]

Solution

As per NCERT, generally the lowest energy structure is the one with the smallest formal charges on the atoms.

Formal charge = V - L - 12S (V = valence electrons, L = non-bonding electrons, S = bonding electrons)

In structure (4), all three O atoms are double bonded to S:

S: 6 - 0 - 12(12) = 0

Each O: 6 - 4 - 12(4) = 0

⇒ All formal charges are zero.

In structure (1), S: 6 - 0 - 12(8) = +2 and each singly bonded O: 6 - 6 - 12(2) = -1, so it carries charge separation.

Structures (2) and (3) do not have three O atoms on S, so they do not represent SO3.

∴ Structure (4) is the most preferred, lowest energy structure.

Answer: (4)

AIPMT 2011 (Mains)

Keep practising — Chemical Bonding and Molecular Structure

2

The pairs of species of oxygen and their magnetic behaviours are noted below. Which of the following presents the correct description?

  1. O2-, O22- – Both diamagnetic
  2. O2+, O2 – Both paramagnetic
  3. O, O22- – Both paramagnetic
  4. O+, O22- – Both paramagnetic
AIPMT 2011 (Mains)
3

Which of the following has the minimum bond length ?

  1. O2+
  2. O2-
  3. O22-
  4. O2
AIPMT 2011 (Prelims)
4

Which of the two ions from the list given below that have the geometry that is explained by the same hybridization of orbitals, NO2-, NO3-, NH2-, NH4+, SCN-?

  1. NO2- and NO3-
  2. NH4+ and NO3-
  3. SCN- and NH2-
  4. NO2- and NH2-
AIPMT 2011 (Prelims)
5

The correct order of increasing bond length of C-H, C-O, C-C and C=C is

  1. C-H < C=C < C-O < C-C
  2. C-C < C=C < C-O < C-H
  3. C-O < C-H < C-C < C=C
  4. C-H < C-O < C-C < C=C
AIPMT 2011 (Prelims)
6

The pairs of species of oxygen and their magnetic behavior are noted below. Which of the following presents the correct description?

  1. O2-, O22- - Both diamagnetic
  2. O+, O22- - Both paramagnetic
  3. O2+, O2 - Both paramagnetic
  4. O, O22- - Both paramagnetic
AIPMT 2011 (Prelims)
7

Considering the state of hybridization of carbon atoms, find out the molecule among the following which is linear ?

  1. CH3-CH=CH-CH3
  2. CH3-C C-CH3
  3. CH2=CH-CH2-C CH
  4. CH3-CH2-CH2-CH3
AIPMT 2011 (Prelims)
8

Which of the following compounds has the lowest melting point?

  1. CaCl2
  2. CaBr2
  3. CaI2
  4. CaF2
Out of syllabusAIPMT 2011 (Prelims)
9

In which of the following molecules the central atom does not have sp3 hybridization?

  1. CH4
  2. SF4
  3. BF4-
  4. NH4+
AIPMT 2010 (Mains)
10

Some of the properties of the two species, NO3- and H3O+ are described below. Which one of them is correct?

  1. Dissimilar in hybridization for the central atom with different structures.
  2. Isostructural with same hybridization for the central atom.
  3. Isostructural with different hybridization for the central atom.
  4. Similar in hybridization for the central atom with different structures.
AIPMT 2010 (Mains)
11

In which of the following pairs of molecules/ ions, the central atoms have sp2 hybridisation ?

  1. NO2- and NH3
  2. BF3 and NO2-
  3. NH2- and H2O
  4. BF3 and NH2-
AIPMT 2010 (Prelims)

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