1
AIEEE 2009
MCQ (Single Correct Answer)
+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 2009
MCQ (Single Correct Answer)
+4
-1
In context with the transition elements, which of the following statements is incorrect ?
A
In addition to the normal oxidation states, the zero oxidation state is also shown by these elements in complexes.
B
In the highest oxidation states, the transition metal show basic character and form cationic complexes.
C
In the highest oxidation states of the first five transition elements (Sc to Mn), all the 4s and 3d electrons are used for bonding
D
Once the d5 configuration is exceeded, the tendency to involve all the 3d electrons in bonding decreases.
3
AIEEE 2008
MCQ (Single Correct Answer)
+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
4
AIEEE 2008
MCQ (Single Correct Answer)
+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
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