Hybridisation sp sp2 sp3 sp3d sp3d2 - UNSOLVED PRACTICE SET

Q7. Define hybridisation. Why do atoms undergo hybridisation?...

Q8. Predict the hybridisation of the central atom in:

(a) BeCl₂

(b) BF₃

(c) CH₄

Q9. Differentiate between sp, sp², and sp³ hybridisation on the basis of:

(a) Number of orbitals mixed

(b) Geometry

(c) Bond angle

Q10. Why does carbon in ethene (C₂H₄) use sp² hybridisation instead of sp³?

Q11. Your art teacher mixes red, blue, and yellow paints to create new colours for a painting. She explains that hybridisation is similar — atomic orbitals mix to create new orbitals with different shapes and properties. If she mixes one s and one p orbital, what "colour" (geometry) does she get? What if she mixes one s and three p orbitals? 

Q12. What is the hybridisation of sulphur in SF₆? Explain how sulphur can expand its octet to accommodate this hybridisation.

Q13. Explain the concept of hybridisation with suitable examples. Describe the formation of:

(a) sp hybrid orbitals (BeCl₂)

(b) sp² hybrid orbitals (BF₃)

(c) sp³ hybrid orbitals (CH₄)

(d) sp³d hybrid orbitals (PCl₅)

(e) sp³d² hybrid orbitals (SF₆)

For each, show the orbital diagram and predict the geometry.

Q14. Discuss the relationship between hybridisation and molecular geometry. Explain how to determine the hybridisation of a central atom using:

(a) The steric number method

(b) The number of sigma bonds and lone pairs

Predict the hybridisation, shape, and bond angles of:

(a) NH₃

(b) H₂O

(c) CO₂

(d) SO₂

Q15. During a chemistry workshop, students are debating the structure of ethyne (C₂H₂).

(a) One student draws the structure H-C≡C-H and claims both carbons are sp hybridised. Verify this using the steric number method.

(b) Explain why the C-C bond in ethyne is shorter and stronger than in ethene or ethane, using hybridisation concepts.

(c) In benzene (C₆H₆), all carbon atoms are sp² hybridised. Explain how this leads to the planar hexagonal structure and the delocalized π electron system.

(d) A student asks: "If diamond has sp³ hybridised carbon and graphite has sp² hybridised carbon, can we have a form of carbon with sp hybridised atoms?" How would you answer, considering carbon allotropes?

Q16. Determine the hybridization of the central atom in the following molecules/ions using the steric number method. Show your calculation.

(a) CO₂

(b) NH₄⁺

(c) SO₂

(d) IF₇

(e) XeO₃F₂

Q17. The C-C bond lengths in different hydrocarbons are:

Ethane (C-C single): 154 pm

Ethene (C=C double): 134 pm

Ethyne (C≡C triple): 120 pm

(a) Explain the trend in bond lengths using hybridisation (sp³, sp², sp).

(b) Calculate the percentage decrease in bond length from ethane to ethene, and from ethene to ethyne.

(c) The C-H bond length in ethane is 109 pm, in ethene is 108 pm, and in ethyne is 106 pm. Explain this trend.

(d) Why does greater s-character in the hybrid orbital lead to shorter and stronger bonds?

Q18. Consider the following molecules and answer the questions:

(a) In CO₂, the carbon atom is sp hybridised. Draw the orbital overlap diagram showing how the two sigma bonds and two pi bonds form.

(b) In ethene (C₂H₄), each carbon is sp² hybridised. Calculate the percentage of s-character and p-character in each hybrid orbital.

(c) In NH₃, nitrogen is sp³ hybridised but the bond angle is 107° instead of 109.5°. Explain this deviation using the concept of lone pair-bond pair repulsion.

(d) In PCl₅, phosphorus uses sp³d hybridisation. Explain why the axial P-Cl bonds (240 pm) are longer than the equatorial P-Cl bonds (202 pm).