1
AIEEE 2009
+4
-1
Knowing that the Chemistry of lanthanoids (Ln) is dominated by its +3 oxidation state, which of the following statements is incorrect ?
A
Because of the large size of the Ln (III) ions the bonding in its compounds is predominantly ionic in character.
B
The ionic sizes of Ln (III) decrease in general with increasing atomic number.
C
Ln (III) compounds are generally colourless
D
Ln (III) hydroxides are mainly basic in character.
2
AIEEE 2008
+4
-1
Larger number of oxidation states are exhibited by the actinoids than those by the lanthanoids, the main reason being
A
4f orbitals more diffused than the 5f orbitals
B
lesser energy difference between 5f and 6d than between 4f and 5d orbitals
C
more energy difference between 5f and 6d than between 4f and 5d orbitals
D
more reactive nature of the actinoids than the lanthanoids
3
AIEEE 2008
+4
-1
Amount of oxalic acid present in a solution can be determined by its titration with $$KMn{O_4}$$ solution in the presence of $${H_2}S{O_4}.$$ The titration gives unsatisfactory result when carried out in the presence of $$HCl,$$ because $$HCl$$
A
gets oxidised by oxalic acid to chlorine
B
furnishes $${H^ + }$$ ions in addition to those from oxalic acid
C
reduces permanganate to $$M{n^{2 + }}$$
D
oxaidises oxalic acid to carbon doxide and water
4
AIEEE 2007
+4
-1
Identify the incorrect statement among the following
A
d-Block elements show irregular and erratic chemical properties among themselves
B
La and Lu have partially filled d orbitals and no other partially filled orbitals
C
The chemistry of various lanthanoids is very similar
D
4f and 5f orbitals are equally shielded
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