For the four successive transition elements (Cr, Mn, Fe and Co), the stability of +2 oxidation state will be there in which of the following order?

Which of the following oxidation states is the most common among the lanthanoids?

Which of the following pairs has the same size?

Solution

Due to lanthanide contraction, the size of Zr and Hf(atom and ions) become nearly similar

Which one of the following ions has electronic configuration[Ar] 3d⁶ ?(At. Nos. Mn =25, Fe = 26, Co = 27,Ni = 28)

Which one of the elements with the following outer orbital configurations may exhibit the largest number of oxidation states?

The correct order of decreasing second ionisation enthalpy of Ti (22), V(23), Cr(24) and Mn (25) is:

Identify the incorrect statement among the following :

Lanthanoid contraction is the accumulation of successive shrinkages.
As a result of lanthanoid contraction, the properties of 4d series of the transition elements have no similarities with the 5d series of elements.
Shielding power of 4 felectrons is quite weak.
There is a decrease in the radii of the atomsor ionsasone proceeds from La to Lu.

Solution

As a result of lanthanoid contraction change in ionic radii on going from elements of 4d to 5d transition series is very small. Thus chemical properties of 4d and 5d

Which one of the following ions is the most stable in aqueous solution?

(At.No. Ti = 22, V = 23, Cr = 24, Mn = 25)

Identify the product and its colour when MnO₂ is fused with solid KOH in the presence of O₂
.

A reduction in atomic size with increase in atomic number is a characteristic of elements of

Solution

Lanthanide contraction results into decrease in atomic and ionicradii.

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