Chapter - 8
d – AND f – BLOCK ELEMENTS
VERY SHORT ANSWER TYPE QUESTIONS
(1 - MARK QUESTIONS)
1. Write the electronic configuration of Cr3+ ion (atomic number of Cr = 24)?
3. Explain CuSO4. 5H2O is blue while ZnSO4 and CuSO4 are colourless?
4. Why is the third ionisation energy of Manganese (Z = 25) is unexpectedly
high?
[Hint : The third electron is to be removed from stable configuration Mn2+
(3d5). It requires higher energy.]
5. Which element among 3d– transition elements, exhibit the highest oxidation
state?
[Hint : Mn (+7)]
6. Silver (Ag) has completely filled d-orbitals (4d10) in its ground state. How
can you say that it is a transition element.
7. In 3d series (Sc → Zn), the enthalpy of atomisation of Zn is low. Why?
[Hint : Poor interatomic bonding in zinc.]
8. Out of the following elements, identify the element which does not exhibit
variable oxidation state?
Cr, Co, Zn.
9. The +3 oxidation state of lanthanum (Z = 57), gadolinium (Z = 64) and
lutetium (Z = 71) are especially stable. Why?
10. Mention one consequence of Lanthanoid Contraction?
11. The first ionization enthalpies of 5d– series elements is higher than those
of 3d and 4d series elements why?
[Hint : Increasing value of effective nuclear charge due to lanthanoid
contraction.]
12. Why Mn2+ compounds are more stable than Fe2+ compounds towards
oxidation to their +3 state?
1
, 14. Calculate the magnetic moment of Cu2+ (Z = 29) on the basis of “spin-only”
formula.
[Hint : µ = n (n + 2) B.M.]
15. What is the shape of chromate ions?
[Hint : Tetrahedral]
16. Why does vanadium pentoxide act a catalyst?
[Hint : In V2O5, Vanadium shows variable oxidation sates.]
17. What are interstitial compounds?
18. The transition metals and their compounds are known for their catalytic
activity. Give two specific reasons to justify the statement.
19. Write the chemical equation for the reaction of thiosulphate ions and
alkaline potassium permanganate.
[Hint : 8MnO4– + 3S2O32– + H2O → 8MnO2 + 2OH– + 6SO42–].
20. Mention the name and formula of the ore from which potassium dichromate
is prepared.
[Hint : FeCr2O4 (Chromite)].
21. Write the electronic configuration of Lu3+ (At. No. = 71).
22. What is the most common oxidation state of actinoids?
23. Write the names of the catalyst used in the :
(a) Manufacture of sulphuric acid by contact process.
(b) Manufacture of polythene.
24. Mention the name of the element among lanthanoids known to exhibit +4
oxidation state.
25. Name one ore each of manganese and chromium.
26. Why is Cd2+ ion white?
*27. Draw the structure of dichromate anion.
*28. Arrange the following monoxides of transition metals on the basis of
decreasing basic character TiO, VO, CrO, FeO.[Hint : TiO > VO > CrO >
FeO]
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d – AND f – BLOCK ELEMENTS
VERY SHORT ANSWER TYPE QUESTIONS
(1 - MARK QUESTIONS)
1. Write the electronic configuration of Cr3+ ion (atomic number of Cr = 24)?
3. Explain CuSO4. 5H2O is blue while ZnSO4 and CuSO4 are colourless?
4. Why is the third ionisation energy of Manganese (Z = 25) is unexpectedly
high?
[Hint : The third electron is to be removed from stable configuration Mn2+
(3d5). It requires higher energy.]
5. Which element among 3d– transition elements, exhibit the highest oxidation
state?
[Hint : Mn (+7)]
6. Silver (Ag) has completely filled d-orbitals (4d10) in its ground state. How
can you say that it is a transition element.
7. In 3d series (Sc → Zn), the enthalpy of atomisation of Zn is low. Why?
[Hint : Poor interatomic bonding in zinc.]
8. Out of the following elements, identify the element which does not exhibit
variable oxidation state?
Cr, Co, Zn.
9. The +3 oxidation state of lanthanum (Z = 57), gadolinium (Z = 64) and
lutetium (Z = 71) are especially stable. Why?
10. Mention one consequence of Lanthanoid Contraction?
11. The first ionization enthalpies of 5d– series elements is higher than those
of 3d and 4d series elements why?
[Hint : Increasing value of effective nuclear charge due to lanthanoid
contraction.]
12. Why Mn2+ compounds are more stable than Fe2+ compounds towards
oxidation to their +3 state?
1
, 14. Calculate the magnetic moment of Cu2+ (Z = 29) on the basis of “spin-only”
formula.
[Hint : µ = n (n + 2) B.M.]
15. What is the shape of chromate ions?
[Hint : Tetrahedral]
16. Why does vanadium pentoxide act a catalyst?
[Hint : In V2O5, Vanadium shows variable oxidation sates.]
17. What are interstitial compounds?
18. The transition metals and their compounds are known for their catalytic
activity. Give two specific reasons to justify the statement.
19. Write the chemical equation for the reaction of thiosulphate ions and
alkaline potassium permanganate.
[Hint : 8MnO4– + 3S2O32– + H2O → 8MnO2 + 2OH– + 6SO42–].
20. Mention the name and formula of the ore from which potassium dichromate
is prepared.
[Hint : FeCr2O4 (Chromite)].
21. Write the electronic configuration of Lu3+ (At. No. = 71).
22. What is the most common oxidation state of actinoids?
23. Write the names of the catalyst used in the :
(a) Manufacture of sulphuric acid by contact process.
(b) Manufacture of polythene.
24. Mention the name of the element among lanthanoids known to exhibit +4
oxidation state.
25. Name one ore each of manganese and chromium.
26. Why is Cd2+ ion white?
*27. Draw the structure of dichromate anion.
*28. Arrange the following monoxides of transition metals on the basis of
decreasing basic character TiO, VO, CrO, FeO.[Hint : TiO > VO > CrO >
FeO]
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