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(A) $1$. Lanthanide contraction is the steady decrease in the atomic and ionic radii of lanthanides with an increase in atomic number.$2$. As we move

Vedclass · Accepted Answer

Poor shielding of one of $4f$ electron by another in the sub-shell.

Vedclass · Answer

(A) $1$. Lanthanide contraction is the steady decrease in the atomic and ionic radii of lanthanides with an increase in atomic number.$2$. As we move from $La$ to $Lu$, electrons are added to the $4f$ subshell.$3$. The $4f$ orbitals have a very diffuse shape, which results in poor shielding of the nuclear charge by the $4f$ electrons.$4$. Due to this poor shielding, the effective nuclear charge experienced by the outer electrons increases, causing the electron cloud to be pulled closer to the nucleus, resulting in a decrease in atomic size.$5$. Therefore, the main cause is the poor shielding of one $4f$ electron by another.

List-$I$ (Element)	List-$II$ (Block)
$(A)$ $Ra$	$(I)$ $p$-block
$(B)$ $Uuq$	$(II)$ $s$-block
$(C)$ $Ds$	$(III)$ $f$-block
$(D)$ $Fm$	$(IV)$ $d$-block

List-$I$ ($\text{Transition metal ion}$)	List-$II$ ($\text{Spin only magnetic moment (B.M.)}$)
$A$. $Ti^{3+}$	$I$. $3.87$
$B$. $V^{2+}$	$II$. $0.00$
$C$. $Ni^{2+}$	$III$. $1.73$
$D$. $Sc^{3+}$	$IV$. $2.84$

List-$I$ (Property)	List-$II$ (Metal)
$A$. Element with maximum second ionization enthalpy	$i$. $Co$
$B$. Element with maximum third ionization enthalpy	$ii$. $Cr$
$C$. $M$ in $M(CO)_6$	$iii$. $Cu$
$D$. Element with maximum enthalpy of atomization	$iv$. $Zn$
	$v$. $Ni$

Which of the following factors may be regarded as the main cause of lanthanide contraction?

Similar Questions

Match the following:
List-$I$ (Element) List-$II$ (Block)
$(A)$ $Ra$ $(I)$ $p$-block
$(B)$ $Uuq$ $(II)$ $s$-block
$(C)$ $Ds$ $(III)$ $f$-block
$(D)$ $Fm$ $(IV)$ $d$-block

The correct answer is

Match List-$I$ with List-$II$:
List-$I$ ($\text{Transition metal ion}$) List-$II$ ($\text{Spin only magnetic moment (B.M.)}$)
$A$. $Ti^{3+}$ $I$. $3.87$
$B$. $V^{2+}$ $II$. $0.00$
$C$. $Ni^{2+}$ $III$. $1.73$
$D$. $Sc^{3+}$ $IV$. $2.84$

Choose the correct answer from the options given below:

Which one of the following statements is true for transition elements?

The calculated magnetic moment (in Bohr magnetons) of $Cu^{2+}$ ion is:

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