Q 1 :    

Which of the following acts as a strong reducing agent?
(Atomic number : Ce = 58, Eu = 63, Gd = 64, Lu = 71)                      [2024]

  • Lu3+

     

  • Ce4+

     

  • Gd3+

     

  • Eu2+

     

(4)

Common oxidation state of Lanthanoids is +3. Ce4+ has tendency to go to Ce3+ hence Ce4+ is good oxidising agent. Eu2+ has tendency to go to Eu3+, hence is good reducing agent.

 



Q 2 :    

The number of element from the following that do not belong to lanthanoids is

Eu, Cm, Er, Tb, Yb and Lu                                   [2024]

  • 5

     

  • 1

     

  • 3

     

  • 4

     

(2)

Lanthanoid series elements are 

La57(Lanthanum), 58Ce(Cerium), 59Pr(Praseodymium), 60Nd(Neodymium), 61Pm(Promethium), Sm62(Samarium), 

63Eu(Europium), 64Gd(Gadolinium), 65Tb(Terbium), 66Dy(Dysprosium), Ho67(Holmium), 68Er(Erbium), 

69Tm(Thulium), 70Yb(Ytterbium), and 71Lu(Lutetium).

Cm96(Curium) is an actinoid.

 



Q 3 :    

The electronic configuration of Einsteinium is

(Given atomic number of Einsteinium = 99)                    [2024]

  • [Rn]5f126d07s2

     

  • [Rn]5f116d07s2

     

  • [Rn]5f136d07s2

     

  • [Rn]5f106d07s2

     

(2)

         Es99=[Rn]865f116d07s2

 



Q 4 :    

Number of colourless lanthanoid ions among the following is _________ .         

Eu3+,Lu3+,Nd3+,La3+,Sm3+                          [2024]



(2)

Lanthonoid ions are coloured because of f-f transitions.

Ions Electronic
configuration
f-f transition Colour
Eu3+ [Xe]544f6 possible Coloured
Lu3+ [Xe]544f14 Not possible as
there are no
unpaired f
electrons
Colourless
Nd3+ [Xe]544f3 possible Coloured
La3+ [Xe]544f0 Not possible as
there are no
f electrons
Colourless
Sm3+ [Xe]544f5 possible Coloured

 



Q 5 :    

Diamagnetic Lanthanoid ions are:                        [2024]

  • Nd3+Eu3+

     

  • La3+Ce4+

     

  • Nd3+Ce4+

     

  • Lu3+Eu3+

     

(2)

Substances that are weakly repelled by magnetic field are called diamagnetic substances. Atoms having all electrons paired are diamagnetic.

 



Q 6 :    

Lanthanoid ions with 4f7 configuration are:                 [2025]

(A)   Eu2+
(B)   Gd3+
(C)   Eu3+
(D)   Tb3+
(E)   Sm2+

  • (A) and (B) only

     

  • (B) and (C) only

     

  • (A) and (D) only

     

  • (B) and (E) only

     

(1)

Ions Electronic configuration
(A)  Eu2+63 [Xe]544f76s0
(B)  Gd3+64 [Xe]544f75d06s0
(C)  Eu3+63 [Xe]544f66s0
(D)  Tb3+65 [Xe]544f86s0
(E)  Sm2+62 [Xe]544f66s0

 



Q 7 :    

Which of the following ions is the strongest oxidizing agent?

(Atomic Number of Ce = 58, Eu = 63, Tb = 65, Lu = 71)                    [2025]

  • Lu3+

     

  • Ce3+

     

  • Eu2+

     

  • Tb4+

     

(4)

+3 is common oxidation states of lanthanoids. Tb4+ has thus a tendency to get reduced to Tb3+ and is an oxidizing agent.