Assignment
No – 2
d
& f – Block Elements
Que
1. Cu+ is not stable in aqueous solution. Why?
Que
2. Which is a stronger reducing agents Cr2+ or Fe2+ and
why?
Que 3. Arrange the following increasing order of acidic character: CrO3, CrO ,
Que 3. Arrange the following increasing order of acidic character: CrO3, CrO ,
Que
4. Calculate the 'spin only' magnetic moment of M2+(aq) ion. (Z=27)
Que
5. Why do Zr and Hf exhibit almost similar properties?
Que
6. Why are Zn, Cd and Hg not regarded as transition elements?
Que
7. What are alloys? Name one important alloy which contains some of the
lanthanoid metals. Mention its use.
Que
8.
La(OH)3 is a stronger base than Lu(OH)3. Why?
Que
9. Lanthanoids form primarily +3 ions, while
the actinoids usually have higher oxidation states in their compounds, +4 or even
+6 being typical.
Que
10. What is meant by the term lanthanoid contraction? What is it due to and
what consequences does it have on the chemistry of elements following
lanthanoids in the periodic table?
Que
11. Compare lanthanoids and actinoids with reference to their: a. Electronic
configuration of atoms b. Oxidation states of elements c. General chemical
reactivity of elements.
Ans
11.
Que
12.
How would you account for the following?
a.
Mn(III) undergoes disproportionation reaction easily.
b.
Co(II) is easily oxidized in the presence of strong ligands.
Q.
13 Give reasons for the following:
i)
First ionisation energies of 5d elements are higher than those of 3d and 4d
elements.
ii)
Actinoid contraction is greater from element to element than lanthanoid
contraction.
Que
14. Explain the following observations about the transition/inner transition
elements:
i)
There is, in general an increase in density of element from titanium (Z=22) to
copper (Z=29). ii) There occurs much more frequent metal‐metal bonding in
compounds of heavy transition elements (3rd series).
iii)
The greatest number of oxidation states are exhibited by the members in the
middle of a transition series.
Q
15: Assign reasons for the following:
a)
The enthalpies of atomization of transition elements are high.
b)
The transition metals and many of their compounds act as good catalysts.
c)
There is a gradual decrease in the atomic sizes of transition elements in a
series with increasing atomic number.
d)
The transition elements have great tendency for complex formation.
e)
Transition metals generally form coloured compounds.
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