Question

27. a)
State the reasons of the following:
i) MnO is basic while MnO, is acidic,
ii) Transition metals show high melting and boiling points.
iii) Zn, Cd and Hg are not regarded as transition metals.
iv) Transition elements show variable oxidation states.​

Answer 1

Answer:

1. Higher oxidation states are short of electrons, meaning they can accept lone pairs and function as Lewis acids. MnO has the lowest oxidation state, so it is the most basic. Mn2O3 is next, then MnO2, and finally Mn2O7 (which is actually acidic)
2. The melting-points of the transition metals are high due to the 3d electrons being available for metallic bonding. The densities of the transition metals are high for the same reason as the high boiling points. ... These properties are the result of metallic bonding between the atoms in the metal lattice.

Explanation:

3. The electronic configurations of Zn, Cd and Hg are represented by the general formula (n-1)d10 ns2. The orbitals in these elements are completely filled in the ground state as well as in their common oxidation states. Therefore, they are not regarded as transition elements

4.Transition elements show variable state oxidation in their compounds. Reason of variable oxidation state is that there is a very small energy difference in between (n-1)d and ns-orbitals. As a result ,electrons of (n-1)d orbitals as well as ns-orbitals take part in bond formation.

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