Q 21 :    

Pair of transition metal ions having the same number of unpaired electrons is :             [2025]
 

• ${\mathrm{V}}^{2+},{\mathrm{Co}}^{2+}$

   

• ${\mathrm{Ti}}^{2+},{\mathrm{Co}}^{2+}$

   

• ${\mathrm{Fe}}^{3+},{\mathrm{Cr}}^{2+}$

   

• ${\mathrm{Ti}}^{3+},{\mathrm{Mn}}^{2+}$

   

Q 22 :    

The correct decreasing order of spin only magnetic moment values (B.M.) of ${\mathrm{Cu}}^{+}$, ${\mathrm{Cu}}^{2+}$, ${\mathrm{Cr}}^{2+}$ and ${\mathrm{Cr}}^{3+}$ ions is :       [2025]

• ${\mathrm{Cu}}^{+}>{\mathrm{Cu}}^{2+}>{\mathrm{Cr}}^{3+}>{\mathrm{Cr}}^{2+}$

   

• ${\mathrm{Cu}}^{2+}>{\mathrm{Cu}}^{+}>{\mathrm{Cr}}^{2+}>{\mathrm{Cr}}^{3+}$

   

• ${\mathrm{Cr}}^{2+}>{\mathrm{Cr}}^{3+}>{\mathrm{Cu}}^{2+}>{\mathrm{Cu}}^{+}$

   

• ${\mathrm{Cr}}^{3+}>{\mathrm{Cr}}^{2+}>{\mathrm{Cu}}^{+}>{\mathrm{Cu}}^{2+}$

   

Q 23 :    

Match List I with List II.         [2025]

	List I		List II
	(Transition metal ion)		(Spin only magnetic moment (B.M.))
A.	${\mathrm{Ti}}^{3+}$	I.	3.87
B.	${\mathrm{V}}^{2+}$	II.	0.00
C.	${\mathrm{Ni}}^{2+}$	III.	1.73
D.	${\mathrm{Sc}}^{3+}$	IV.	2.84

 

Choose the correct answer from the options given below:

• A–III, B–I, C–IV, D–II

   

• A–III, B–I, C–II, D–IV

   

• A–IV, B–II, C–III, D–I

   

• A–II, B–IV, C–I, D–III

   

Q 24 :    

The correct option with order of melting points of the pairs (Mn, Fe), (Tc, Ru) and (Re, Os) is :   [2025]

• Mn < Fe, Tc < Ru and Os < Re

   

• Fe < Mn, Ru < Tc and Re < Os

   

• Mn < Fe, Tc < Ru and Re < Os

   

• Fe < Mn, Ru < Tc and Os < Re

   

Q 25 :    

The element that does not belong to the same period of the remaining elements (modern periodic table) is :  [2025]

• Platinum

   

• Osmium

   

• Palladium

   

• Iridium

   

Q 26 :    

The number of valence electrons present in the metal among Cr, Co, Fe and Ni which has the lowest enthalpy of atomisation is  [2025]

• 8

   

• 9

   

• 1

   

• 10

   

Q 27 :    

The first transition series metal ‘M’ has the highest enthalpy of atomisation in its series. One of its aquated ions (${\mathrm{Mn}}^{+}$) exists in green colour. The nature of the oxide formed by the above ${\mathrm{Mn}}^{-}$ ion is :  [2025]

• neutral 

   

• acidic

   

• basic

   

• amphoteric

   

Q 28 :    

Among Sc, Mn, Co and Cu, identify the element with highest enthalpy of atomisation. The spin only magnetic moment value of that element in its +2 oxidation state is _____ B.M (in nearest integer).                [2025]

Q 29 :    

Niobium (Nb) and ruthenium (Ru) have $“x”$ and $“y”$ number of electrons in their respective 4d orbitals. The value of $x+y$ is _______.         [2025]

Q 30 :    

The spin only magnetic moment ($\mathrm{\mu }$) value (B.M.) of the compound with strongest oxidising power among ${\mathrm{Mn}}_2{\mathrm{O}}_3$, TiO and VO is _______ B.M. (Nearest integer).      [2025]