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d- and f-Block Elements · Question 44

AIPMT 2012 (Mains)MCQEasy📈 Topic in 25% papers+4−1
1

The catalytic activity of transition metals and their compounds is ascribed mainly to

  1. their magnetic behaviour
  2. their unfilled d-orbitals
  3. their ability to adopt variable oxidation states
  4. their chemical reactivity

Answer

(3) their ability to adopt variable oxidation states

Solution

As per NCERT, the catalytic activity of transition metals and their compounds is attributed to their ability to adopt multiple (variable) oxidation states and to form complexes.

They form unstable intermediates with the reactants and change their oxidation state easily, providing a path of lower activation energy, e.g. Fe3+ catalyses the reaction between iodide and persulphate ions:

2Fe3+ + 2I- 2Fe2+ + I2

2Fe2+ + S2O82- 2Fe3+ + 2SO42-

Answer: (3)

AIPMT 2012 (Mains)

Keep practising — d- and f-Block Elements

2

Which of the following exhibits only + 3 oxidation state?

  1. U
  2. Th
  3. Ac
  4. Pa
AIPMT 2012 (Mains)
3

Which one of the following does not correctly represent the correct order of the property indicated against it?

  1. Ti < V < Cr < Mn : increasing number of oxidation states
  2. Ti3+ < V3+ < Cr3+ < Mn3+ : increasing magnetic moment
  3. Ti < V < Cr < Mn : increasing melting points
  4. Ti < V < Mn < Cr : increasing 2nd ionization enthalpy
AIPMT 2012 (Mains)
4

Four successive members of the first series of the transition metals are listed below. For which one of them the standard potential ( E M2+/M ) value has a positive sign?

  1. Co (Z = 27)
  2. Ni (Z = 28)
  3. Cu (Z = 29)
  4. Fe (Z = 26)
AIPMT 2012 (Mains)
5

Identify the alloy containing a non-metal as a constituent in it.

  1. Invar
  2. Steel
  3. Bell metal
  4. Bronze
AIPMT 2012 (Prelims)
6

Which of the statements is not true?

  1. On passing H2S through acidified K2Cr2O7 solution, a milky colour is observed.
  2. Na2Cr2O7 is preferred over K2Cr2O7 in volumetric analysis.
  3. K2Cr2O7 solution in acidic medium is orange.
  4. K2Cr2O7 solution becomes yellow on increasing the pH beyond 7.
AIPMT 2012 (Prelims)
7

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? (At. nos. Cr = 24, Mn = 25, Fe = 26, Co = 27)

  1. Mn > Fe > Cr > Co
  2. Fe > Mn > Co > Cr
  3. Co > Mn > Fe > Cr
  4. Cr > Mn > Co > Fe
AIPMT 2011 (Prelims)
8

Acidified K2Cr2O7 solution turns green when Na2SO3 is added to it. This is due to the formation of

  1. Cr2(SO4)3
  2. CrO42-
  3. Cr2(SO3)3
  4. CrSO4
AIPMT 2011 (Prelims)
9

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

  1. 4
  2. 2
  3. 5
  4. 3
AIPMT 2010 (Mains)
10

Which of the following ions will exhibit colour in aqueous solutions?

  1. La3+ (Z = 57)
  2. Ti3+ (Z = 22)
  3. Lu3+ (Z = 71)
  4. Sc3+ (Z = 21)
AIPMT 2010 (Prelims)
11

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

  1. Ni3+
  2. Mn3+
  3. Fe3+
  4. Co3+
AIPMT 2010 (Prelims)

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