d and f BLOCK ELEMENTS

What is the significance of comparing calculated and observed E° values in Fig. 4.4?

• It proves the thermochemical model is completely accurate.
• It shows that calculations are always more accurate than experiments.
• It indicates that thermochemical parameters are unreliable.
• It highlights deviations from the simple thermochemical model, indicating additional stabilizing factors for certain elements.

Why is the d3 configuration (t2g^3) particularly stable in an octahedral field?

• Because it has paired electrons.
• Because it is a high-spin configuration.
• Because it occupies the eg orbitals.
• Due to the symmetrical distribution of electrons in the lower energy t2g orbitals, minimizing repulsion.

Which of the following best describes the relationship between ionization enthalpies and the E°(M2+/M) trend across the transition series?

• Decreasing ionization enthalpies generally lead to E°(M2+/M) values becoming less negative.
• Ionization enthalpies remain constant, so they do not affect the E°(M2+/M) trend.
• Ionization enthalpies decrease sharply, causing E°(M2+/M) to become more negative.
• Increasing ionization enthalpies generally lead to E°(M2+/M) values becoming less negative.

What is the main thermodynamic reason why copper does not react with dilute H2SO4?

• Copper is too dense.
• Dilute H2SO4 is not a strong enough acid.
• The negative E°(Cu2+/Cu) makes the cell potential for the reaction positive.
• The positive E°(Cu2+/Cu) makes the cell potential for the reaction negative.

If an element in the transition series has an E°(M2+/M) value significantly more negative than its neighbors, what could be a likely electronic reason?

• Its M2+ ion has a very high charge density.
• Its atomic radius is significantly smaller.
• Its ionization enthalpies are significantly lower.
• Its M2+ ion achieves a particularly stable electronic configuration (e.g., d5 or d10).