441.

Identify the metal that forms colourless compounds.

• Iron (Z = 26)

• Chromium (Z = 24)

• Vanadium (Z=23)

• Scandium (Z =21)

Consider the following statements.

I. La(OH)₃ is the least basic among hydroxides of lanthanides.

II. Zr⁴⁺ and Hf⁴⁺ possess almost the same ionic radii.

III. Ce⁴⁺ can act as an oxidising agent.

Which of the above is/are true?

• I and III

• II and III

• II only

• I and II

Pick out the correct statement(s).

1. Manganese exhibits +7 oxidation state
2. Zinc forms coloured ions
3. [CoF₆]^3- is diamagnetic
4. Sc forms +4 oxidation state
5. Zn exhibits only +2 oxidation state

• 1 and 2

• 1 and 5

• 2 and 4

• 3 and 4

The maximum oxidation state exhibited by actinide ions is

• +5

• +4

• +7

• +8

Pick out the correct statements from the following

1.Cobalt (III) is more stable in octahedral complexes.

2. Zinc forms coloured ions or complexes.

3. Most of the d-block elements and their compounds are ferromagnetic.

4. Osmium shows (VIII) oxidation state.

5. Cobalt (II) is more stable in octahedral complex.

• 1 and 2

• 1 and 3

• 2 and 4

• 1 and 4

Which of the following statements is not correct?

• The complexes [NiCl₄]^2- and [Ni(CN)₄]^2- differ in the state of hybridization of nickel

• The complexes [NiCl₄]^2- and [Ni(CN)₄]^2- differ in the magnetic properties

• The complexes [NiCl₄]^2- and [Ni(CN)₄]^2- differ in geometry

• The complexes [NiCl₄]^2- and [Ni(CN)₄]^2- differ in primary valencies of nickel

Which one of the following pairs of elements is called 'chemical twins' because of their very similar chemical properties ?

• Mn and W

• Mo and Tc

• Fe and Re

• Hf and Zr

Effective magnetic rnoment of Sc³⁺ ion is :

• 1.73

• 0

• 5.92

• 2.83

Potassium permanganate acts as an oxidant in alkaline and acidic media. The final products formed from KMnO₄ in the two conditions are respectively

• MnO^2- and Mn³⁺

• Mn³⁺ and Mn²⁺

• Mn²⁺ and Mn³⁺

• MnO₂ and Mn²⁺

The catalytic activity of the transition metals and their compounds is described to :

• their chemical reactivity 

• their magnetic behaviour

• their unfilled d-orbitals

• their ability to adopt multiple oxidation states and their complexing ability