Indian Forest Service (Mains), Chemistry optional · 2022 · Paper I

Q3(a). Molecular orbitals of linear BeH₂

10 marks
Topic: Chemical bonding
Question only

Question

Draw the MO diagram of BeH₂. Sketch the electron density boundary surface for σg (ψ₁) and σu* (ψ₆). Show the combination of atomic orbitals of H atoms and Be atom for the σg and σu* orbitals.

Model answer

The free solution for 2022 answers questions 1, 2, 4, 5 and 6, the ones picked in its time plan. Question 3 is answered in full in the IFoS Chemistry Paper I, 2021 to 2025 book, with every part of every paper.

Read the 2022 solution

Part of VKC Basic

Read the key points and the full model answer with VKC Basic

VKC Basic (₹999 for 6 months) opens every solved answer, the notes, the handbook and the daily answer archive. Every Mains test series includes it.

See what is included Already a member? Sign in

Printed copy and Kindle

UPSC Indian Forest Service (Main) Chemistry Paper I: Model Answers 2021 to 2025

All eight questions of each paper, with the question printed above its answer
Physical chemistry numericals worked with units; inorganic structures drawn
Topic-wise weightage and a topic-wise index

Printed copy Kindle edition Read sample pages

Topic notes: molecular orbital theory: LCAO, MO diagrams of N₂, O₂, CO, NO, CN⁻ and HF, bond order and magnetism, with every Civil Services, IFoS and Geo-Scientist PYQ →

CoversBeH2 MO diagrammolecular orbital theorysymmetry-adapted linear combinationssigma g and sigma ulinear triatomic

All parts of Question 3

3(a) Molecular orbitals of linear BeH₂10 marks
3(b)(i) Adiabatic mixing of ice and hot water10 marks
3(b)(ii) Trouton rule5 marks
3(c) Sulfur phase diagram and metastability15 marks