d and f BLOCK ELEMENTS

In the series Sc (Z = 21) to Zn (Z = 30), why is the enthalpy of atomisation of zinc the lowest?

• Zinc has the highest nuclear charge
• Zinc has a completely filled 3d subshell, resulting in weaker metallic bonding
• Zinc has the largest atomic radius
• Zinc forms only ionic bonds

Why does the trend of increasing second ionisation enthalpy sometimes break in the 3d series?

• Due to the complete filling of the 3d subshell
• Due to the attainment of a stable d5 configuration in the resulting ion
• Due to the decrease in atomic radius
• Due to the increase in nuclear charge

What is the primary reason for the relatively small increase in first ionisation enthalpy across the 3d transition series (Sc to Zn)?

• The 4s electrons are held very tightly by the nucleus
• Effective shielding of 4s electrons by the increasing number of 3d electrons
• The nuclear charge remains constant
• The atomic radii increase significantly

Why do transition elements generally exhibit higher enthalpies of atomisation compared to s-block elements?

• Due to their low atomic radii
• Due to the presence of a large number of unpaired electrons leading to stronger interatomic interactions
• Due to their high ionisation enthalpies
• Due to their complete outer electron shells

What is the electronic configuration of the Ni2+ ion?

• [Ar] 3d6
• [Ar] 3d7
• [Ar] 3d8
• [Ar] 3d9