d and f BLOCK ELEMENTS

What is the primary structural feature of the f-block that explains its position in the periodic table?

• Large atomic sizes
• High radioactivity
• The filling of inner (n-2)f or (n-3)f orbitals rather than outer valence orbitals
• Gaseous state

What is the main reason why the successive ionization enthalpies of transition elements do not increase as steeply as main group elements?

• d electrons are easier to remove than s electrons
• d electrons are harder to remove than p electrons
• d electrons are not as tightly held as outermost s/p electrons but more so than next shell electrons
• All d electrons are equivalent in energy

Why do the melting and boiling points of transition elements tend to peak around the middle of each series?

• Maximum atomic mass in the middle
• Maximum ionic charge in the middle
• Optimal number of unpaired d electrons for strong bonding
• Decreasing atomic radii across the series

What type of catalyst is primarily involved in the Haber process for ammonia synthesis?

• Homogeneous catalyst
• Enzymatic catalyst
• Heterogeneous catalyst
• Acid-base catalyst

What is the primary reason transition metal oxides dissolve in both acids and bases?

• They are always basic
• They are always acidic
• They can react with both H+ and OH- ions due to their amphoteric nature
• They are neutral oxides