NVAEasyJEE 2023VSEPR Theory & Shapes of Molecules

JEE Chemistry 2023 Question with Solution

The number of bent-shaped molecule(s) from the following is: N3\mathrm{N_3^-}, NO2\mathrm{NO_2^-}, I3\mathrm{I_3^-}, O3\mathrm{O_3}, SO2\mathrm{SO_2}

Answer

Correct answer:3

Step-by-step solution

Standard Method

Given: N3\mathrm{N_3^-}, NO2\mathrm{NO_2^-}, I3\mathrm{I_3^-}, O3\mathrm{O_3}, SO2\mathrm{SO_2}

Find: The number of species having bent shape.

From the solution content:

  • SO2\mathrm{SO_2} has bent molecular geometry.
  • O3\mathrm{O_3} has bent molecular geometry.
  • I3\mathrm{I_3^-} has linear geometry.
  • N3\mathrm{N_3^-} is linear.

For the remaining species NO2\mathrm{NO_2^-}, the bent shape follows from its molecular geometry with a lone pair on the central atom.

Therefore, the bent-shaped species are NO2\mathrm{NO_2^-}, O3\mathrm{O_3} and SO2\mathrm{SO_2}.

So, the required number is 33.

Structures of sulfur dioxide, ozone, triiodide ion and azide ion showing bent and linear molecular geometries with lone pairs marked.

Shape-wise Classification

Given: Five species are listed.

Identify principle: Use molecular shape classification.

  1. SO2\mathrm{SO_2} (bent)
  2. O3\mathrm{O_3} (bent)
  3. I3\mathrm{I_3^-} (linear)
  4. N3\mathrm{N_3^-} (linear)
  5. NO2\mathrm{NO_2^-} (bent)

Hence, total number of bent species is

33

Therefore, the answer is 33.

Common mistakes

  • Treating NO2\mathrm{NO_2^-} as linear is incorrect because the central nitrogen has a lone pair, which gives a bent molecular shape. Check the electron-pair arrangement before deciding the geometry.

  • Confusing electron geometry with molecular geometry leads to errors. For species like SO2\mathrm{SO_2} and O3\mathrm{O_3}, lone pairs change the molecular shape to bent even though the electron-domain arrangement is trigonal planar.

  • Assuming every three-atom species is bent is incorrect. N3\mathrm{N_3^-} and I3\mathrm{I_3^-} are linear, so shape must be decided species by species.

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