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Chemical Bonding and Molecular Structure · Question 98

AIPMT 2004MCQMedium📈 Topic in 75% papers+4−1
1

In BrF3 molecule, the lone pairs occupy equatorial positions to minimize

  1. lone pair - bond pair repulsion only
  2. bond pair - bond pair repulsion only
  3. lone pair - lone pair repulsion and lone pair - bond pair repulsion
  4. lone pair - lone pair repulsion only.

Answer

(4) lone pair - lone pair repulsion only.

Solution

In BrF3, Br has 3 bond pairs + 2 lone pairs = 5 electron pairs ⇒ sp3d, trigonal bipyramidal arrangement.

As per NCERT (VSEPR theory), the repulsion order is lone pair–lone pair > lone pair–bond pair > bond pair–bond pair, and the strongest repulsion, lone pair–lone pair at 90 , must be avoided first.

⇒ With both lone pairs in equatorial positions they are 120 apart, so no lone pair–lone pair repulsion at 90 remains.

If one lone pair were axial, the two lone pairs would be at 90 to each other (strong lone pair–lone pair repulsion).

∴ The lone pairs occupy equatorial positions to minimize lone pair–lone pair repulsion, giving a bent T-shaped molecule.

Answer: (4)

AIPMT 2004

Keep practising — Chemical Bonding and Molecular Structure

2

Which one of the following statements is not correct for sigma- and pi- bonds formed between two carbon atoms?

  1. sigma-bond is stronger than a pi-bond.
  2. Bond energies of sigma- and pi-bonds are of the order of 264 kJ/mol and 347 kJ/mol, respectively
  3. Free rotation of atoms about a sigma-bond is allowed but not in case of a pi-bond.
  4. Sigma-bond determines the direction between carbon atoms but a pi-bond has no primary effect in this regard.
AIPMT 2003
3

Which of the following has p - d bonding?

  1. NO3-
  2. SO32-
  3. BO33-
  4. CO32-
AIPMT 2002
4

In NO3- ion number of bond pair and lone pair of electrons on nitrogen atom are

  1. 2, 2
  2. 3, 1
  3. 1, 3
  4. 4, 0
AIPMT 2002
5

Main axis of a diatomic molecule is z, atomic orbitals px and py overlap to form which of the following orbitals.

  1. molecular orbital
  2. molecular orbital
  3. molecular orbital
  4. No bond will form
AIPMT 2001
6

Which of the following two are isostructural?

  1. XeF2, IF2-
  2. NH3, BF3
  3. CO32-, SO32-
  4. PCl5, ICl5
AIPMT 2001
7

In which of the following bond angle is maximum ?

  1. NH3
  2. NH4+
  3. PCl3
  4. SCl2
AIPMT 2001
8

In X-H Y, X and Y both are electronegative elements. Then

  1. electron density on X will increase and on H will decrease
  2. in both electron density will increase
  3. in both electron density will decrease
  4. on X electron density will decrease and on H will increase.
AIPMT 2001
9

d - p bond present in

  1. CO32-
  2. PO43-
  3. NO3-
  4. NO2-
AIPMT 2000
10

Right order of dissociation energy N2 and N2+ is

  1. N2 > N2+
  2. N2 = N2+
  3. N2+ > N2
  4. none
AIPMT 2000
11

Which species does not exhibit paramagnetism?

  1. N2+
  2. O2-
  3. CO
  4. NO
AIPMT 2000

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