321721
Assertion : \(\mathrm{C e^{4+}}\) is a good oxidising agent. Reason : \(\mathrm{\mathrm{Sm}^{2+}}\) is a good reducing agent.
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but reason is correct.
Explanation:
In +4 state, Ce is most oxidizing because it can give an electron to become more stable at +3 state. Whereas in \(\mathrm{\mathrm{Sm}^{+2}}\), the lanthanides are more stable in +3 state and hence in +2 state it gets oxidized easily (good reducing agent) to get to +3 oxidation state.
CHXII08:THE D- & F-BLOCK ELEMENTS
321722
\(\mathrm{\mathrm{KMnO}_{4}}\) and \(\mathrm{\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}}\) are replaced in volumetric analysis by
1 La (III) salts
2 \(\mathrm{\mathrm{Ce}}\) (III) salts
3 \(\mathrm{\mathrm{Ce}}\) (IV) salts
4 Gd (III) salts
Explanation:
Conceptual Questions
CHXII08:THE D- & F-BLOCK ELEMENTS
321723
Assertion : \(\mathrm{La}(\mathrm{OH})_{3}\) is more basic than \(\mathrm{Lu}(\mathrm{OH})_{3}\). Reason : Size of \(\mathrm{Ln}^{3+}\) ions increases along the lanthanoid series and shows less covalent character
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but Reason is correct.
Explanation:
Due to lanthanide contraction, the size of \(\mathrm{Lu}^{3+}\) is decreased, then, covalent character of hydroxides increases and hence the basic strength decreases. Thus, \(\mathrm{La}(\mathrm{OH})_{3}\) is more ionic and thus, more basic. Thus, option (3) is correct.
CHXII08:THE D- & F-BLOCK ELEMENTS
321724
Assertion : Most of the trivalent lanthanide ions are coloured both in the solid state and in aqueous solution. Reason : The elements with \({\rm{xf}}\) electrons have a similar colour to those of \({\rm{(14 - x) f}}\) electrons.
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but Reason is correct.
Explanation:
Lanthanide ions exhibit distinct colors owing to the partially filled f-orbitals within their electronic configurations. This unique characteristic allows for \(\mathrm{f}\)-f transitions, leading to the absorption of specific wavelengths of light and the manifestation of various colors in these ions. As f subshell can have a maximum of 14 electrons, xf and (14-x) f, both will have the same number of unpaired electrons for transition .Hence,they both show same color. So option (2) is correct.
CHXII08:THE D- & F-BLOCK ELEMENTS
321725
The pair of lanthanoid ions which are diamagnetic is
1 \({\mathrm{\mathrm{Ce}^{4+}}}\) and \({\mathrm{\mathrm{Yb}^{2+}}}\)
2 \({\mathrm{\mathrm{Ce}^{3+}}}\) and \({\mathrm{\mathrm{Eu}^{2+}}}\)
3 \({\mathrm{\mathrm{Gd}^{3+}}}\) and \({\mathrm{\mathrm{Eu}^{3+}}}\)
4 \({\mathrm{\mathrm{Pm}^{3+}}}\) and \({\mathrm{\mathrm{Sm}^{3+}}}\)
Explanation:
If ion does not contain unpaired electrons, It is diamagnetic. \({\mathrm{\mathrm{f}^{\circ}, \mathrm{f}^{14}}}\) configurations are diamagnetic.
321721
Assertion : \(\mathrm{C e^{4+}}\) is a good oxidising agent. Reason : \(\mathrm{\mathrm{Sm}^{2+}}\) is a good reducing agent.
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but reason is correct.
Explanation:
In +4 state, Ce is most oxidizing because it can give an electron to become more stable at +3 state. Whereas in \(\mathrm{\mathrm{Sm}^{+2}}\), the lanthanides are more stable in +3 state and hence in +2 state it gets oxidized easily (good reducing agent) to get to +3 oxidation state.
CHXII08:THE D- & F-BLOCK ELEMENTS
321722
\(\mathrm{\mathrm{KMnO}_{4}}\) and \(\mathrm{\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}}\) are replaced in volumetric analysis by
1 La (III) salts
2 \(\mathrm{\mathrm{Ce}}\) (III) salts
3 \(\mathrm{\mathrm{Ce}}\) (IV) salts
4 Gd (III) salts
Explanation:
Conceptual Questions
CHXII08:THE D- & F-BLOCK ELEMENTS
321723
Assertion : \(\mathrm{La}(\mathrm{OH})_{3}\) is more basic than \(\mathrm{Lu}(\mathrm{OH})_{3}\). Reason : Size of \(\mathrm{Ln}^{3+}\) ions increases along the lanthanoid series and shows less covalent character
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but Reason is correct.
Explanation:
Due to lanthanide contraction, the size of \(\mathrm{Lu}^{3+}\) is decreased, then, covalent character of hydroxides increases and hence the basic strength decreases. Thus, \(\mathrm{La}(\mathrm{OH})_{3}\) is more ionic and thus, more basic. Thus, option (3) is correct.
CHXII08:THE D- & F-BLOCK ELEMENTS
321724
Assertion : Most of the trivalent lanthanide ions are coloured both in the solid state and in aqueous solution. Reason : The elements with \({\rm{xf}}\) electrons have a similar colour to those of \({\rm{(14 - x) f}}\) electrons.
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but Reason is correct.
Explanation:
Lanthanide ions exhibit distinct colors owing to the partially filled f-orbitals within their electronic configurations. This unique characteristic allows for \(\mathrm{f}\)-f transitions, leading to the absorption of specific wavelengths of light and the manifestation of various colors in these ions. As f subshell can have a maximum of 14 electrons, xf and (14-x) f, both will have the same number of unpaired electrons for transition .Hence,they both show same color. So option (2) is correct.
CHXII08:THE D- & F-BLOCK ELEMENTS
321725
The pair of lanthanoid ions which are diamagnetic is
1 \({\mathrm{\mathrm{Ce}^{4+}}}\) and \({\mathrm{\mathrm{Yb}^{2+}}}\)
2 \({\mathrm{\mathrm{Ce}^{3+}}}\) and \({\mathrm{\mathrm{Eu}^{2+}}}\)
3 \({\mathrm{\mathrm{Gd}^{3+}}}\) and \({\mathrm{\mathrm{Eu}^{3+}}}\)
4 \({\mathrm{\mathrm{Pm}^{3+}}}\) and \({\mathrm{\mathrm{Sm}^{3+}}}\)
Explanation:
If ion does not contain unpaired electrons, It is diamagnetic. \({\mathrm{\mathrm{f}^{\circ}, \mathrm{f}^{14}}}\) configurations are diamagnetic.
321721
Assertion : \(\mathrm{C e^{4+}}\) is a good oxidising agent. Reason : \(\mathrm{\mathrm{Sm}^{2+}}\) is a good reducing agent.
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but reason is correct.
Explanation:
In +4 state, Ce is most oxidizing because it can give an electron to become more stable at +3 state. Whereas in \(\mathrm{\mathrm{Sm}^{+2}}\), the lanthanides are more stable in +3 state and hence in +2 state it gets oxidized easily (good reducing agent) to get to +3 oxidation state.
CHXII08:THE D- & F-BLOCK ELEMENTS
321722
\(\mathrm{\mathrm{KMnO}_{4}}\) and \(\mathrm{\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}}\) are replaced in volumetric analysis by
1 La (III) salts
2 \(\mathrm{\mathrm{Ce}}\) (III) salts
3 \(\mathrm{\mathrm{Ce}}\) (IV) salts
4 Gd (III) salts
Explanation:
Conceptual Questions
CHXII08:THE D- & F-BLOCK ELEMENTS
321723
Assertion : \(\mathrm{La}(\mathrm{OH})_{3}\) is more basic than \(\mathrm{Lu}(\mathrm{OH})_{3}\). Reason : Size of \(\mathrm{Ln}^{3+}\) ions increases along the lanthanoid series and shows less covalent character
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but Reason is correct.
Explanation:
Due to lanthanide contraction, the size of \(\mathrm{Lu}^{3+}\) is decreased, then, covalent character of hydroxides increases and hence the basic strength decreases. Thus, \(\mathrm{La}(\mathrm{OH})_{3}\) is more ionic and thus, more basic. Thus, option (3) is correct.
CHXII08:THE D- & F-BLOCK ELEMENTS
321724
Assertion : Most of the trivalent lanthanide ions are coloured both in the solid state and in aqueous solution. Reason : The elements with \({\rm{xf}}\) electrons have a similar colour to those of \({\rm{(14 - x) f}}\) electrons.
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but Reason is correct.
Explanation:
Lanthanide ions exhibit distinct colors owing to the partially filled f-orbitals within their electronic configurations. This unique characteristic allows for \(\mathrm{f}\)-f transitions, leading to the absorption of specific wavelengths of light and the manifestation of various colors in these ions. As f subshell can have a maximum of 14 electrons, xf and (14-x) f, both will have the same number of unpaired electrons for transition .Hence,they both show same color. So option (2) is correct.
CHXII08:THE D- & F-BLOCK ELEMENTS
321725
The pair of lanthanoid ions which are diamagnetic is
1 \({\mathrm{\mathrm{Ce}^{4+}}}\) and \({\mathrm{\mathrm{Yb}^{2+}}}\)
2 \({\mathrm{\mathrm{Ce}^{3+}}}\) and \({\mathrm{\mathrm{Eu}^{2+}}}\)
3 \({\mathrm{\mathrm{Gd}^{3+}}}\) and \({\mathrm{\mathrm{Eu}^{3+}}}\)
4 \({\mathrm{\mathrm{Pm}^{3+}}}\) and \({\mathrm{\mathrm{Sm}^{3+}}}\)
Explanation:
If ion does not contain unpaired electrons, It is diamagnetic. \({\mathrm{\mathrm{f}^{\circ}, \mathrm{f}^{14}}}\) configurations are diamagnetic.
321721
Assertion : \(\mathrm{C e^{4+}}\) is a good oxidising agent. Reason : \(\mathrm{\mathrm{Sm}^{2+}}\) is a good reducing agent.
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but reason is correct.
Explanation:
In +4 state, Ce is most oxidizing because it can give an electron to become more stable at +3 state. Whereas in \(\mathrm{\mathrm{Sm}^{+2}}\), the lanthanides are more stable in +3 state and hence in +2 state it gets oxidized easily (good reducing agent) to get to +3 oxidation state.
CHXII08:THE D- & F-BLOCK ELEMENTS
321722
\(\mathrm{\mathrm{KMnO}_{4}}\) and \(\mathrm{\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}}\) are replaced in volumetric analysis by
1 La (III) salts
2 \(\mathrm{\mathrm{Ce}}\) (III) salts
3 \(\mathrm{\mathrm{Ce}}\) (IV) salts
4 Gd (III) salts
Explanation:
Conceptual Questions
CHXII08:THE D- & F-BLOCK ELEMENTS
321723
Assertion : \(\mathrm{La}(\mathrm{OH})_{3}\) is more basic than \(\mathrm{Lu}(\mathrm{OH})_{3}\). Reason : Size of \(\mathrm{Ln}^{3+}\) ions increases along the lanthanoid series and shows less covalent character
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but Reason is correct.
Explanation:
Due to lanthanide contraction, the size of \(\mathrm{Lu}^{3+}\) is decreased, then, covalent character of hydroxides increases and hence the basic strength decreases. Thus, \(\mathrm{La}(\mathrm{OH})_{3}\) is more ionic and thus, more basic. Thus, option (3) is correct.
CHXII08:THE D- & F-BLOCK ELEMENTS
321724
Assertion : Most of the trivalent lanthanide ions are coloured both in the solid state and in aqueous solution. Reason : The elements with \({\rm{xf}}\) electrons have a similar colour to those of \({\rm{(14 - x) f}}\) electrons.
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but Reason is correct.
Explanation:
Lanthanide ions exhibit distinct colors owing to the partially filled f-orbitals within their electronic configurations. This unique characteristic allows for \(\mathrm{f}\)-f transitions, leading to the absorption of specific wavelengths of light and the manifestation of various colors in these ions. As f subshell can have a maximum of 14 electrons, xf and (14-x) f, both will have the same number of unpaired electrons for transition .Hence,they both show same color. So option (2) is correct.
CHXII08:THE D- & F-BLOCK ELEMENTS
321725
The pair of lanthanoid ions which are diamagnetic is
1 \({\mathrm{\mathrm{Ce}^{4+}}}\) and \({\mathrm{\mathrm{Yb}^{2+}}}\)
2 \({\mathrm{\mathrm{Ce}^{3+}}}\) and \({\mathrm{\mathrm{Eu}^{2+}}}\)
3 \({\mathrm{\mathrm{Gd}^{3+}}}\) and \({\mathrm{\mathrm{Eu}^{3+}}}\)
4 \({\mathrm{\mathrm{Pm}^{3+}}}\) and \({\mathrm{\mathrm{Sm}^{3+}}}\)
Explanation:
If ion does not contain unpaired electrons, It is diamagnetic. \({\mathrm{\mathrm{f}^{\circ}, \mathrm{f}^{14}}}\) configurations are diamagnetic.
321721
Assertion : \(\mathrm{C e^{4+}}\) is a good oxidising agent. Reason : \(\mathrm{\mathrm{Sm}^{2+}}\) is a good reducing agent.
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but reason is correct.
Explanation:
In +4 state, Ce is most oxidizing because it can give an electron to become more stable at +3 state. Whereas in \(\mathrm{\mathrm{Sm}^{+2}}\), the lanthanides are more stable in +3 state and hence in +2 state it gets oxidized easily (good reducing agent) to get to +3 oxidation state.
CHXII08:THE D- & F-BLOCK ELEMENTS
321722
\(\mathrm{\mathrm{KMnO}_{4}}\) and \(\mathrm{\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}}\) are replaced in volumetric analysis by
1 La (III) salts
2 \(\mathrm{\mathrm{Ce}}\) (III) salts
3 \(\mathrm{\mathrm{Ce}}\) (IV) salts
4 Gd (III) salts
Explanation:
Conceptual Questions
CHXII08:THE D- & F-BLOCK ELEMENTS
321723
Assertion : \(\mathrm{La}(\mathrm{OH})_{3}\) is more basic than \(\mathrm{Lu}(\mathrm{OH})_{3}\). Reason : Size of \(\mathrm{Ln}^{3+}\) ions increases along the lanthanoid series and shows less covalent character
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but Reason is correct.
Explanation:
Due to lanthanide contraction, the size of \(\mathrm{Lu}^{3+}\) is decreased, then, covalent character of hydroxides increases and hence the basic strength decreases. Thus, \(\mathrm{La}(\mathrm{OH})_{3}\) is more ionic and thus, more basic. Thus, option (3) is correct.
CHXII08:THE D- & F-BLOCK ELEMENTS
321724
Assertion : Most of the trivalent lanthanide ions are coloured both in the solid state and in aqueous solution. Reason : The elements with \({\rm{xf}}\) electrons have a similar colour to those of \({\rm{(14 - x) f}}\) electrons.
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but Reason is correct.
Explanation:
Lanthanide ions exhibit distinct colors owing to the partially filled f-orbitals within their electronic configurations. This unique characteristic allows for \(\mathrm{f}\)-f transitions, leading to the absorption of specific wavelengths of light and the manifestation of various colors in these ions. As f subshell can have a maximum of 14 electrons, xf and (14-x) f, both will have the same number of unpaired electrons for transition .Hence,they both show same color. So option (2) is correct.
CHXII08:THE D- & F-BLOCK ELEMENTS
321725
The pair of lanthanoid ions which are diamagnetic is
1 \({\mathrm{\mathrm{Ce}^{4+}}}\) and \({\mathrm{\mathrm{Yb}^{2+}}}\)
2 \({\mathrm{\mathrm{Ce}^{3+}}}\) and \({\mathrm{\mathrm{Eu}^{2+}}}\)
3 \({\mathrm{\mathrm{Gd}^{3+}}}\) and \({\mathrm{\mathrm{Eu}^{3+}}}\)
4 \({\mathrm{\mathrm{Pm}^{3+}}}\) and \({\mathrm{\mathrm{Sm}^{3+}}}\)
Explanation:
If ion does not contain unpaired electrons, It is diamagnetic. \({\mathrm{\mathrm{f}^{\circ}, \mathrm{f}^{14}}}\) configurations are diamagnetic.
