The d- and f-Block Elements

Which of the following statements regarding transition elements is correct?

1. They generally form only colourless compounds.
2. They cannot form complex compounds.
3. They readily form interstitial compounds with small atoms such as hydrogen, carbon and nitrogen.
4. They exhibit only one oxidation state.

Which pair of elements has nearly identical atomic radii due to lanthanoid contraction?

1. Sodium and Potassium
2. Calcium and Strontium
3. Zirconium and Hafnium
4. Copper and Silver

Which statement correctly distinguishes actinoids from lanthanoids?

1. Actinoids show only the +3 oxidation state.
2. Actinoids exhibit greater variability in oxidation states than lanthanoids.
3. Lanthanoids are radioactive, whereas actinoids are not.
4. Actinoids contain completely filled 4f orbitals.

Which of the following is the most common oxidation state of lanthanoids?

1. +1
2. +2
3. +3
4. +6

The gradual decrease in the size of lanthanoid ions with increasing atomic number is known as:

1. Shielding effect
2. Lanthanoid contraction
3. Inert pair effect
4. Diagonal relationship

The orange colour of potassium dichromate is due to the presence of:

1. Cr2+
2. Cr3+
3. Cr2O7^2-
4. CrO4^2-

Which of the following compounds acts as a strong oxidizing agent in acidic medium?

1. KCl
2. KMnO4
3. NaCl
4. CuSO4

Steel is an example of:

1. An interstitial compound
2. A coordination compound
3. An alloy
4. An ionic compound

Transition elements are widely used as catalysts because they:

1. Have low melting points.
2. Can exhibit variable oxidation states and form intermediate complexes.
3. Are highly reactive with water.
4. Have completely filled d-orbitals.

The paramagnetic nature of transition metal ions is mainly due to the presence of:

1. Paired electrons
2. Completely filled d-orbitals
3. Unpaired electrons
4. High atomic mass

Which one of the following is the highest oxidation state shown by manganese?

1. +2
2. +4
3. +6
4. +7

Which of the following transition metal ions is colourless in aqueous solution?

1. Ti3+
2. Cu2+
3. Mn2+
4. Sc3+

The variable oxidation states shown by transition elements are mainly due to:

1. Large atomic radius
2. Similar energies of ns and (n-1)d orbitals
3. High ionization enthalpy
4. Low density

Which property is mainly responsible for the formation of coloured compounds by transition metals?

1. High density
2. Presence of partially filled d-orbitals
3. Large atomic size
4. High melting point

Which of the following elements is not considered a transition element according to the IUPAC definition?

1. Iron (Fe)
2. Copper (Cu)
3. Zinc (Zn)
4. Chromium (Cr)