Q10 of 26 Page 1

Why do transition elements show variable oxidation states? In 3d series (Sc to Zn), which element shows the maximum number of oxidation states and why?

In d-block elements, incomplete filling of d orbitals is observed. So, they exhibit variable oxidation state. In 3d series Mn shows maximum number of oxidation states as it occurs in the middle of the series.

Explanation: Elements found at the beginning of 3d series have less electrons to share or lose. For example, Sc has the outer electronic configuration of 3d24s1 and so its oxidation state is +3 only. While those found at the end of the series have too many electrons to make them oarticipate in bonding. For example, Zn has the outer electronic configuration of 3d104s2 and so it’s maximum possible oxidation state is +2.


More from this chapter

All 26 →
8

Name the reagents used in the following reactions:

(i)


(ii)



9

(a) Following reactions occur at cathode during the electrolysis of aqueous copper(II) chloride solution:


On the basis of their standard reduction electrode potential (E0) values, which reaction is feasible at the cathode and why?


(b) State Kohlrausch law of independent migration of ion. Write its one application.


 11

Calculate the mass of Nacl (molar mass = 58.5 g mol-1) to be dissolved in 37.2g of water to lower the freezing point by 20C, assuming that NaCl undergoes complete dissociation. (Kf for water = 1.86 K kg mol-1).

 12

Write the names and structures of the monomers of the following polymers:

(i) Terylene


(ii) Bakelite


(iii) Buna-S