AH Prelim Quiz

What is the principle of Le Chatelier's principle in chemical equilibrium?

• The principle states that if a system at equilibrium is disturbed, it will completely shift to a new equilibrium position

• The principle states that if a system at equilibrium is disturbed by a change in temperature, pressure, or concentration of reactants or products, the system will shift its position to counteract the effect of the disturbance.

• The principle states that if a system at equilibrium is disturbed, it will remain unchanged

• Le Chatelier's principle only applies to reactions involving gases

What is the expression for the equilibrium constant for dissociation of methanoic acid?

• K_a =

  H⁺ x CH₃COO^-/ CH₃COOH

• K_a =

  H⁺ x CH₃COO^-/ CH₃COOH x H₂O

• K_a =

  [H⁺] [CH₃COO^-]/ [CH₃COOH]

• K_a =

  [H⁺] [CH₃COO^-]/ [CH₃COOH][H₂O]

What is the pH of a 0.005 mol l^-1 calcium hydroxide solution?

• 2

• 2.3

• 11.7

• 12

What are the characteristic properties of transition metals?

• High melting and boiling points, variable oxidation states, formation of colored compounds, and the ability to form complex ions

• Low melting and boiling points, variable oxidation states, formation of colored compounds, and the ability to form simple ions

• Low melting and boiling points, fixed oxidation states, formation of colorless compounds, and the inability to form complex ions

• High melting and boiling points, fixed oxidation states, formation of colorless compounds, and the inability to form complex ions

Explain the formation of colored compounds in transition metals.

• Formation of colored compounds is due to the presence of paired s electrons in the outermost energy level

• Colored compounds are formed due to the presence of unpaired p electrons in the outermost energy level

• The color in transition metals is caused by the presence of unpaired f electrons in the outermost energy level

• Presence of unpaired d electrons in the outermost energy level

How do transition metals act as heterogeneous catalysts in various chemical reactions?

• By changing their oxidation state

• By increasing the activation energy and slowing down the reaction

• By changing the chemical composition of the reactants

• By providing a surface for the reaction to occur and lowering the activation energy using their incomplete d orbitals

What is the significance of atomic spectra in the study of atomic structure?

• Atomic spectra help in understanding the energy levels of electrons in an atom.

• Atomic spectra are not related to the energy levels of electrons

• Atomic spectra only provide information about the nucleus of the atom

• Atomic spectra have no significance in the study of atomic structure

Explain the difference between emission and absorption spectra in atomic physics.

• Emission spectra occur when an atom reflects light, while absorption spectra occur when an atom refracts light.

• Emission spectra occur when an atom emits light, while absorption spectra occur when an atom absorbs light.

• Emission spectra occur when an atom absorbs light, while absorption spectra occur when an atom emits light.

• Emission spectra occur when an atom absorbs energy, while absorption spectra occur when an atom emits energy.

What is the only factor that changes the value of an equilibrium constant for a reaction?

What is the oxidation number of manganese in MnO₂?