Chemistry - 2013 E.C (2020/2021) Ethiopian University Entrance Exam (EUEE)

A 1s² 2s² 2p⁶ 3s² 3p⁶ 4s³ 3d⁶

B 1s² 2s² 2p⁶ 3s² 3p⁶ 4s³ 3d⁴

C 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁴

D 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁵

A maximum number of unpaired electrons with parallel spins

B two electrons of opposite spins placed in the first orbitals

C maximum number of unpaired electrons with opposite spins

D two electrons of parallel spins placed in the first orbital

A elements with similar properties are placed in the same period

B non-metals are placed on the right side of the periodic table

C transition and inner-transition elements are placed in the middle of the periodic table

D metals are placed on the right hand side of the periodic table

A Na is oxidized at the anode

B Cl₂ is formed at the cathode

C O₂ is produced at the anode due to the oxidation of water

D The net reaction produces Cl₂ at the anode and Na at the cathode.

A The presence of NH₄⁺ ion suppresses the dissociation of the weak based NH₄OH.

B The NH₄⁺ ion is a spectator ion in the reaction mixture.

C The reaction equilibrium is shifted towards the right due to the presence of NH₄⁺ ions.

D The presence of NH₄⁺ in the reaction mixture makes the solution more basic.

A At 40 ^oC pure water is no more neutral

B Water dissociates to a higher extent at 40 ^oC than at 25 ^oC.

C Hydroxyl ion concentration is higher at 40^o than hydrogen ion concentration

D Hydrogen ion concentration at 25 ^oC is higher than at 40 ^oC.

A loss of electrons and decrease in oxidation number

B gain of electrons and increase in oxidation number

C gain of electrons and no change in oxidation number

D gain of electrons and decrease in oxidation number

A Anode = SO₄^2- (aq) + 4H⁺ (aq) +2e^- → SO₂ (g) + 2H₂O, Cathode=2H⁺ (aq) + 2e^- → H₂ (g)

B Anode=4OH(aq) → H₂O(l) + O₂(g) +4e^-, Cathode=2H⁺ (aq) +2e^- → H₂ (g)

C Anode= 2H₂O(l) → O₂(g) + 4H⁺(aq) +4e^-, Cathode=2H⁺ (aq) +2e^- → H₂ (g)

D Anode=4OH(aq) → H₂O(l) + O₂(g) +4e^-, Cathode=2H₂O (l) +2e^- → H₂ (g) + 2OH^-(aq)

A The overall cell potential is calculated by the formula E°_cell=E_Cathode − E_Anode

B Electrons flow spontaneously from negative to positive electrodes

C The difference in the electrical potential of the electrode is positive that is positive cell

D E°_cell is greater than zero for non-spontaneous process

A The overall cell potential is calculated by the formula E°_cell=E°_cathode - E°_anode

B Electrons flow spontaneously from negative to positive electrodes.

C The difference in the electrical potential of the electrode is positive that is positive cell.

D E°_cell is greater than zero for non-spontaneous process.