What is meant by variable oxidation states?

Give reason: (i) Transition metals show variable oxidation states. (ii) Actinoids show wide range of oxidation states.

How can we show that change in oxidation state is different from variable oxidation state for non transition element ?

Why do transition elements show variable oxidation state?

Which one of the following does not exhibit variable oxidation states?

Why do alkali metals not show variable oxidation states ?

Which transition element does not exhibit variable oxidation state?

Give reason for the following : (i) Mn shows the highest oxidation state of +7 with oxygen but with fluorine, it shows the highest oxidation state of +4 (ii) Transition metals show variable oxidation states. (iii) Actinoids show irregularities in their electronic configurations.

(a) Why do transition elements show variable oxidation states? (i) Name the element showing maximum number of oxidation states among the first series of transition metals from Sc (Z = 21) to Zn (Z = 30). (ii) Name the element which shows only + 3 oxidation state. (b) What is lanthanoid contraction? Name an important alloy which contains some of the lanthanoid metals.

Assertion (A): Barium is not required for normal biological function in human beings. Reason (R ): Barium does not show variable oxidation states.

Assertion : All halogens undergo disproportionation reaction in alkaline medium. Reason : All halogens exhibit variable oxidation states.