The correct answer is option 3. All of their ions are coloured.
Let us look into each statement in detail:
(1) They show variable oxidation states:
Transition metals, which are d-block elements, often have electrons in their outer d orbitals. These d electrons can be involved in bonding, and the transition metals can exhibit multiple oxidation states because the d orbitals are available for gaining or losing electrons. This property is particularly characteristic of the transition metals in the middle of the d-block.
(2) They exhibit paramagnetic and diamagnetic properties:
Many transition metals have unpaired electrons in their d orbitals. Unpaired electrons lead to magnetic moments, making the substances paramagnetic, meaning they are attracted to a magnetic field. However, some transition metal ions or complexes may be diamagnetic if all electrons are paired, meaning they are not attracted to a magnetic field.
(3) All of their ions are colored:
This statement is not correct. While many transition metal ions are indeed colored, not all of them exhibit color. The color in transition metal ions is often associated with the transition of electrons between different d orbitals. For example, the presence of unpaired electrons in partially filled d orbitals can lead to absorption of visible light, resulting in color. However, some transition metal ions, especially those with completely filled d orbitals, may not show color.
(4) They exhibit catalytic property:
Transition metals and their compounds are known for their catalytic properties. This is due to their ability to undergo changes in oxidation states, form complexes, and participate in redox reactions. Many industrial processes involve the use of transition metal catalysts to increase the rate of reactions or to facilitate specific chemical transformations.
In summary, statements (1), (2), and (4) are correct, while statement (3) is not correct as not all transition metal ions exhibit color. |
