Lanthanoid's most common oxidation state is:
1. 2
2. 5
3. 3
4. 4
Which of the following exhibits only a +3 oxidation state?
1. | Th | 2. | Ac |
3. | Pa | 4. | U |
Four successive members of the first series of the transition metals are listed below. For which one of them does the standard potential value have a positive sign?
1. Ni (Z = 28)
2. Cu (Z = 29)
3. Fe (Z = 26)
4. Co (Z = 27)
Which one of the following does not correctly represent the correct order of the property indicated against it?
1. | Ti3+< V3+< Cr3+< Mn3+: increasing magnetic moment |
2. | Ti < V < Cr < Mn : increasing melting point |
3. | Ti < V < Mn < Cr : increasing 2nd ionization enthalpy |
4. | Ti < V < Cr < Mn : increasing number of oxidation states |
The catalytic activity of transition metals and their compounds is ascribed mainly to:
1. their unfilled d-orbitals
2. their ability to adopt variable oxidation states
3. their chemical reactivity
4. their magnetic behaviour
1. | Both Sc3+ and Zn2+ ions are colourless and form white compounds |
2. | In the case of Sc, 3d orbitals are partially filled but in Zn, these are fully filled. |
3. | The last electron is assumed to be added to the 4s level in the case of Zn |
4. | Both Sc and Zn do not exhibit variable oxidation states. |
Actinoids exhibit more oxidation states than lanthanoids. The main reason for this is:
1. | More energy difference between 5f and 6d orbitals than that between 4f and 5d orbitals |
2. | Greater metallic character of the lanthanoids than that of the corresponding actinoids |
3. | The lesser energy difference between 5f and 6d orbitals than that between 4f and 5d orbitals |
4. | More active nature of the actinoids |
The d-electron configurations of Cr2+, Mn2+, Fe2+ and Ni2+ and 3d4, 3d5, 3d6 and 3d8 respectively.
Which one of the following aqua complexes will exhibit the minimum paramagnetic behaviour?
(At. No. Cr = 24, Mn = 25, Fe = 26, Ni = 28)
1. \(\left[\mathrm{Mn}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{2+}\)
2. \(\left[\mathrm{Fe}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{2+}\)
3. \(\left[\mathrm{Ni}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{2+}\)
4. \(\left[\mathrm{Cr}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{2+}\)
Which one of the following ions is the most stable in an aqueous solution?
(At. No. Ti = 22, V = 23, Cr = 24, Mn = 25)
1. \(\text{Cr}^{3 +}\)
2. \(\text V^{3 +}\)
3. \(\text{Ti}^{3 +}\)
4. \(\text{Mn}^{3 +}\)