Chemistry Exam Questions - Grade 12 ESSLCE 2023

Chemistry - Grade 12 -2023 G.C

Grade 12 students can now access their exam results by visiting the Educational Assessment and Examination Services (EAES) website.

15. Which one of the following reactions would occur spontaneously in an aqueous solution at 25°C? Assume that the initial concentrations of the dissolved species are all 1.0 M.

Half reaction E°(V)
${Sn}^{2 +} (aq) + 2 e^{-}$ ➝ $Sn (s)$ -0.14
${Br}_{2} (l) + 2 e^{-}$ → $2 {Br}^{-} (aq)$ +1.07
${Ag}^{+} (aq) + e^{-}$ → $Ag (s)$ +0.80
${Ni}^{2+} (aq) + 2 e^{-}$ → $Ni (s)$ -0.25
${Ca}^{2+} (aq) + 2 e^{-}$ → $Ca (s)$ -2.87
${Cd}^{2+} (aq) + 2 e^{-}$ → $Cd (s)$ -0.40
${Cu}^{2+} (aq) + e^{-}$ → ${Cu}^{+} (aq)$ +0.15
${Fe}^{3+} (aq)$ → ${Fe}^{2+} (aq)$ +0.77

Half reaction	E°(V)
${Sn}^{2 +} (aq) + 2 e^{-}$ ➝ $Sn (s)$	-0.14
${Br}_{2} (l) + 2 e^{-}$ → $2 {Br}^{-} (aq)$	+1.07
${Ag}^{+} (aq) + e^{-}$ → $Ag (s)$	+0.80
${Ni}^{2+} (aq) + 2 e^{-}$ → $Ni (s)$	-0.25
${Ca}^{2+} (aq) + 2 e^{-}$ → $Ca (s)$	-2.87
${Cd}^{2+} (aq) + 2 e^{-}$ → $Cd (s)$	-0.40
${Cu}^{2+} (aq) + e^{-}$ → ${Cu}^{+} (aq)$	+0.15
${Fe}^{3+} (aq)$ → ${Fe}^{2+} (aq)$	+0.77

Ca(s)+Cd2+(aq) → ${Ca}^{2+} (aq) + Cd (s)$ " > $Ca (s) + {Cd}^{2+} (aq)$ → ${Ca}^{2+} (aq) + Cd (s)$
Cu2+(aq)+Fe2+(aq) → ${Cu}^{+} (aq) + {Fe}^{3+} (aq)$ " > ${Cu}^{2+} (aq) + {Fe}^{2+} (aq)$ → ${Cu}^{+} (aq) + {Fe}^{3+} (aq)$
2Br-(aq)+Sn2+(aq) → ${Br}_{2} (1) + Sn (s)$ " > $2 {Br}^{-} (aq) + {Sn}^{2+} (aq)$ → ${Br}_{2} (1) + Sn (s)$
2Ag(s)+Ni2+(aq) → $2 {Ag}^{+} (aq) + Ni (s)$ " > $2 Ag (s) + {Ni}^{2+} (aq)$ → $2 {Ag}^{+} (aq) + Ni (s)$

16. Which one of the following is the main reason for the large difference in dipole-moment between the triatomic molecules water (H₂O) and carbon dioxide (CO₂)?

The bonds in carbon dioxide (CO₂) are directed 180° and bond polarity reinforces each other.
The presence of multiple bonds in carbon dioxide (CO₂) while single bonds in water.
The higher electronegativity difference among atoms in water (H₂O) than in carbon dioxide (CO₂).
The presence of lone pairs of electrons in water (H₂O) partially reinforces bond polarities.

17. How many non-bonding pairs of electrons are present in the valence shell of the central atom in CIF₃?

18. Which one would be observed in a laboratory activity that is applied on naphthalene?

It is soluble in water.
It shows relatively high melting point.
It conducts electricity in molten state.
It is soluble in benzene.

19. Which one of the following statements is CORRECT?

Valence bond model explain molecular shape from the interaction of atomic orbitals.
In Lewis model, electrons repel one another and a pair of bonding electrons lies far apart as possible.
Lewis model predicts the shapes, of molecules based on electron-pair repulsions around a central atom.
Valence bond model simply shows the linkage between atoms and the presence of lone pairs.

We have provided these questions from previous years grade 12 Ethiopian Secondary School Leaving Certificate Examination (ESSLCE) exams with the sole purpose of assisting students in their studies and preparations for upcoming exams. Please be aware that these questions are not indicative of future exam content. Good luck with your studies!

16. Which one of the following is the main reason for the large difference in dipole-moment between the triatomic molecules water (H₂O) and carbon dioxide (CO₂)?

17. How many non-bonding pairs of electrons are present in the valence shell of the central atom in CIF3?

18. Which one would be observed in a laboratory activity that is applied on naphthalene?

19. Which one of the following statements is CORRECT?

17. How many non-bonding pairs of electrons are present in the valence shell of the central atom in CIF₃?