D and F Block Elements MCQ Questions & Answers in Inorganic Chemistry | Chemistry
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241.
Which of the following has been arranged in order of increasing bond strength?
Due to poor shielding of $$4f$$ electrons, bond strength is maximum for $$H{g^ + } - H{g^ + }.$$
242.
Among the following series of transition metal ions, the one in which all metal ions have $$3{d^2}$$ electronic configuration is
$$\left( {{\text{At}}{\text{. no}}{\text{.}}\,Ti = 22,V = 23,} \right.$$ $$\left. {Cr = 24,Mn = 25} \right)$$
A
$$T{i^{3 + }},{V^{2 + }},C{r^{3 + }},M{n^{4 + }}$$
B
$$T{i^ + },{V^{4 + }},C{r^{6 + }},M{n^{7 + }}$$
C
$$T{i^{4 + }},{V^{3 + }},C{r^{2 + }},M{n^{3 + }}$$
D
$$T{i^{2 + }},{V^{3 + }},C{r^{4 + }},M{n^{5 + }}$$
243.
A compound of a metal ion $${M^{x + }}\left( {Z = 24} \right)$$ has a spin only magnetic moment of $$\sqrt {15} $$ Bohr Magnetons. The number of unpaired electrons in the compound are
A
2
B
4
C
5
D
3
Answer :
3
Magnetic moment $$\mu = \sqrt {n\left( {n + 2} \right)} $$ where $$n = $$ number of unpaired electrons
$$\eqalign{
& \sqrt {15} = \sqrt {n\left( {n + 2} \right)} \cr
& \therefore \,\,n = 3 \cr} $$
244.
Lanthanoides and actinoides resemble in
A
Electronic configuration
B
Oxidation state
C
Ionization energy
D
Formation of complexes
Answer :
Oxidation state
The oxidation state in both ( lanthanide and actinide ) is $$+3.$$ The property of actinide are very similar to those of lanthanide when both are in $$+3$$ state.
245.
Mercury is the only metal which is liquid at $${0^ \circ }C.$$ This is due to its
A
very high ionisation energy and weak metallic bond.
B
low ionisation potential.
C
high atomic weight.
D
high vapour pressure.
Answer :
very high ionisation energy and weak metallic bond.
Metallic bonding in mercury is weak.
246.
The correct order of ionic radii of $$Ce,La,Pm$$ and $$Yb$$ in +3 oxidation state is
The overall decrease in atomic and ionic radii from $$L{a^{3 + }}$$ to $$L{u^{3 + }}$$ is called lanthanoid contraction. Hence, the correct order is $$Y{b^{3 + }} < P{m^{3 + }} < C{e^{3 + }} < L{a^{3 + }}$$
247.
Which is the non-lanthanide element?
A
$$La$$
B
$$Lu$$
C
$$Pr$$
D
$$Pm$$
Answer :
$$La$$
Lanthanum is a $$d$$ - block element which resembles lanthanides.
248.
Which of the following are basic oxides?
$$M{n_2}{O_7},{V_2}{O_3},{V_2}{O_5},CrO,C{r_2}{O_3}$$
A
$$M{n_2}{O_7}\,{\text{and}}\,{V_2}{O_3}$$
B
$${V_2}{O_3}\,{\text{and}}\,CrO$$
C
$$CrO\,{\text{and}}\,C{r_2}{O_3}$$
D
$${V_2}{O_5}\,{\text{and}}\,{V_2}{O_3}$$
Answer :
$${V_2}{O_3}\,{\text{and}}\,CrO$$
In case of transition metal oxides, the oxides with metals in lower oxidation states are basic in nature.
$$O.S.$$ of $$Mn$$ in $$M{n_2}{O_7} = + 7;V$$ in $${V_2}{O_3} = + 3;V$$ in $${V_2}{O_5} = + 5;Cr$$ in $$CrO = + 2;Cr$$ in $$C{r_2}{O_3} = + 3$$
Thus in $${V_2}{O_3},CrO$$ and $$C{r_2}{O_3}$$ transition metal ion is in lower oxidation state but $$C{r_2}{O_3}$$ is amphoteric in nature. Hence $${V_2}{O_3}$$ and $$CrO$$ are basic in nature.
249.
Which one of the following elements shows maximum number of different oxidation states in its compounds ?
A
$$Eu$$
B
$$La$$
C
$$Gd$$
D
$$Am$$
Answer :
$$Am$$
We know that lanthanides $$La,Gd$$ shows $$+3,$$ oxidation state, while $$Eu$$ shows oxidation state of $$+2$$ and $$+ 3.$$ Am shows $$+3,$$ $$+4, +5$$ and $$+6$$ oxidation states. Therefore Americium $$(Am)$$ has maximum number of oxidation states.
250.
A blue colouration is not obtained when
A
ammonium hydroxide dissolves in copper sulphate.
B
copper sulphate solution reacts with $${K_4}\left[ {Fe{{\left( {CN} \right)}_6}} \right].$$