d- and f-Block Elements · Question 39

Which of the following statements about the interstitial compounds is incorrect?

1. They are much harder than the pure metal.
2. They have higher melting points than the pure metal.
3. They retain metallic conductivity.
4. They are chemically reactive.

Which of the following lanthanoid ions is diamagnetic? (At. nos. Ce = 58, Sm = 62, Eu = 63, Yb = 70)

1. Eu2+
2. Yb2+
3. Ce2+
4. Sm2+

The outer electronic configuration of Gd (At. No. 64) is

1. 4f5 5d4 6s1
2. 4f7 5d1 6s2
3. 4f3 5d5 6s2
4. 4f4 5d5 6s1

Sc (Z = 21) is a transition element but Zn (Z = 30) is not because

1. both Sc3+ and Zn2+ ions are colourless and form white compounds.
2. in case of Sc, 3d orbitals are partially filled but in Zn these are filled.
3. last electron is assumed to be added to 4s level in case of Zn.
4. both Sc and Zn do not exhibit variable oxidation states.

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

Which of the following exhibits only + 3 oxidation state?

1. U
2. Th
3. Ac
4. Pa

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

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)

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

1. Invar
2. Steel
3. Bell metal
4. Bronze

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.