Answers MCQs
Assignment – 1
d & f – Block Elements
Ans 1. (3) It can be seen after losing 2 electrons, Mn has 3d5 configuration which is exactly half filled. More energy is required to remove the third electron.

Ans 2. (1) Sc3+ has d0 configuration thus its aqueous solution is colourless. Only those salts give colour in aqueous solution whose ions contain unpaired electrons in the d-subshell.

Ans 3. (4) In the transition elements, the energies of (n-1)d orbitals and ns orbitals are very close. Hence, electrons from both can participate in bonding. Hence option (4) will have maximum oxidation sates.

Ans 4. (1)
The outer configuration are: Co: 3d7 4s2
Ni: 3d8 4s2
Mn: 3d5 4s2
Fe: 3d4 4s2
To form tripositve ion, each atom has to lose three electrons each. Thus, the given configuration matches with that of Co3+ ion.

Ans 5. d of both (b) and (c)

Ans 6. c (first increases to a maximum and then decreases)

Ans 7. b (Ti3+)

Ans 8. b (Cuprous ion has a complete d-orbital and cupric ion has an incomplete d-orbital)

Ans 9. d (TiF62- and Cu2Cl2)

Ans 10. b (b. 3d5 4s1)

Ans 11. c (the valence shell electrons of 5d elements experience greater effective nuclear charge than 3d- and 4d-elements due to poor shielding of 4f subshell electrons)

Ans 12. C (Fe3+)

Ans 13. c (availability of d-orbitals for bonding)

Ans 14. d (incomplete (n-1)d subshell)

Ans 15. c (3d34s2)

Ans 16. a (Ti4+)