Neco Model Questions Vol1 2021 Chemistry Question 3

Practice essay / theory question 3 from the 2021 Neco Model Questions Vol1 Chemistry examination. This question covers Chemical Bonding .

Neco Model Questions Vol1 2021 Chemistry Essay / Theory
Topic: Chemical Bonding
Question 3 NECO_MODEL_QUESTIONS_VOL1 • 2021 • CHEMISTRY • essay

A binary compound MN₂ is formed between element M (group 15, electronegativity 2.1) and element N (group 16, electronegativity 3.5). The compound is a colourless solid with a melting point of 150 °C. For comparison, the ionic compound NaCl has a lattice energy of 787 kJ mol⁻¹ and a melting point of 801 °C.

Question Parts

( a )
Using the electronegativity values, state whether the M–N bond is ionic, polar covalent or non‑polar covalent. Justify your answer.
( b )
Predict the hybridisation and the molecular geometry around the central atom N in MN₂. Give a brief justification using VSEPR theory.
( c )
Explain why MN₂ has a much lower melting point than the ionic solid NaCl, even though both contain the same number of atoms per formula unit.
( d )
MN₂ is insoluble in water but dissolves readily in a non‑polar organic solvent such as benzene. Discuss the nature of the intermolecular forces that account for this solubility behaviour.

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About This Question

This is Neco Model Questions Vol1 2021 Chemistry Question 3. It is one of the essay questions from the 2021 Neco Model Questions Vol1 Chemistry examination.

The question covers Chemical Bonding .

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