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CAIE A-Level Chemistry 3.5 Shapes of molecules Question Bank

Practise using VSEPR to predict shapes, bond angles and angle changes in molecules and ions from electron-pair repulsion evidence.

Syllabus
2028–2030
Course
Chemistry 9701
Level
AS

Exam points

  • order labelled bond angles in diagrams using lone-pair and bonding-pair repulsions

Covered syllabus points

3.5.1—The shapes of, and bond angles in, molecules3.5.2—The shapes of, and bond angles in, molecules

3.5 Shapes of molecules question 1

[Maximum number: 1]

Sulfides are compounds that contain sulfur but not oxygen.

Carbon disulfide, CS2\mathrm{CS}_{2}, is a volatile liquid at room temperature and pressure.

Suggest the bond angle in a molecule of CS2\mathrm{CS}_{2}.

3.5 Shapes of molecules question 2

[Maximum number: 1]

Nitrogen and phosphorus are elements in Group 15 of the Periodic Table.

A common test for nitrates is the reaction with NaOH and Al . Equation 1 shows the reaction.

 equation 13NO3−+8Al+5OH−+18H2O→3NH3+8[Al(OH)4]−\text { equation } 1 \quad 3 \mathrm{NO}_{3}^{-}+8 \mathrm{Al}+5 \mathrm{OH}^{-}+18 \mathrm{H}_{2} \mathrm{O} \rightarrow 3 \mathrm{NH}_{3}+8\left[\mathrm{Al}(\mathrm{OH})_{4}\right]^{-}

Suggest the shape of the [Al(OH)4]−\left[\mathrm{Al}(\mathrm{OH})_{4}\right]^{-}ion.

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