1. The electron configuration of iron in FeO₄^2- ion is

• 1s² 2s² 2p⁶ 3s² 3p⁶ 3d²

• 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶

• 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵ 4s¹

• 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²

Which statement is true about transition elements, vanadium to copper, in the Periodic Table?

• The atomic size decreases.

• The 4s orbital is fully-filled.

• The most stable oxidation state is +2.

• The first ionization energies are almost similar

In general, block-d elements(scandium to zinc) have high melting points. Which statement can best explain this physical property?

• The screening effect is high.

• The structure is close-packed.

• The ionization energy is high.

• The metallic bonding involves 3d and 4s electrons

Titanium and calcium are in the same period in the Periodic Table. Which property of titanium is lower or smaller than that of calcium?

• Density

• Atomic size

• Melting point

• Electrical conductivity

Which of the following d-block elements has the largest number of unpaired electrons?

• Titanium

• Manganese

• Chromium

• Copper

An element Z forms Z²⁺ ion with the configuration of [Ar]3d⁸. If the relative atomic mass of Z is given by the expression of 2x + 3, where x is the proton number of Z, what is the number of neutrons in the nucleus of Z?

• 26

• 28

• 29

• 31

The third ionisation energy of iron is lower than manganese because

• the Fe²⁺ has a stable d⁵ configuration.

• the Mn²⁺ ion has a stable d⁵ configuration.

• all the 3d sub-shells in iron is fully filled.

• iron is more reactive than manganese.

The melting and boiling point of manganese is the lowest among the first row of d-block elements because

• Manganese is a metalloid.

• Manganese has a fully-filled 3d sub-shell

• The intermolecular forces are the weak van der Waals forces

• Manganese is a non-metal

Write the electronic configuration for Cr³⁺.

Transition elements is _______________