D and F Block Elements MCQ Questions & Answers in Inorganic Chemistry | Chemistry
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171.
The colour of light absorbed by an aqueous solution of $$CuS{O_4}$$ is:
A
orange-red
B
blue-green
C
yellow
D
violet
Answer :
orange-red
$$CuS{O_4}$$ will be absorbing orange-red colour and hence will be of blue colour.
172.
Reason of lanthanoid contraction is
A
negligible screening effect of $$f$$-orbitals
B
increasing nuclear charge
C
decreasing nuclear charge
D
decreasing screening effect
Answer :
negligible screening effect of $$f$$-orbitals
Lanthanoid contraction is the regular decrease in atomic and ionic radii of lanthanides. This is due to the imperfect shielding [ or poor screening effect ] of $$f$$-orbitals due to their diffused shape which unable to counterbalance the effect to the increased nuclear charge. Hence, the net result is a contraction in size of lanthanoids.
173.
Transition metals make the most efficient catalysts because of their ability to
A
adopt multiple oxidation states and to form complexes
B
form coloured ions
C
show paramagnetism due to unpaired electrons
D
form a large number of oxides
Answer :
adopt multiple oxidation states and to form complexes
No explanation is given for this question. Let's discuss the answer together.
174.
Match the column I with column II and mark the appropriate choice.
Column I
Column II
a.
An element which can show +8 oxidation state
1.
$$Ce$$
b.
An element with +7 as the most stable oxidation state in its oxides
2.
$$Pm$$
c.
Radioactive lanthanoid
3.
$$Os$$
d.
Lanthanoid which shows +4 oxidation state
4.
$$Mn$$
A
a - 1, b - 2, c - 3, d - 4
B
a - 2, b - 3, c - 4, d - 1
C
a - 4, b - 1, c - 2, d - 3
D
a - 3, b - 4, c - 2, d - 1
Answer :
a - 3, b - 4, c - 2, d - 1
No explanation is given for this question. Let's discuss the answer together.
175.
Consider the following statements
(i) $$La{\left( {OH} \right)_3}$$ is least basic among hydroxides of lanthanides.
(ii) $$Z{r^{4 + }}$$ and $$H{f^{4 + }}$$ possess almost the same ionic radii.
(iii) $$C{e^{4 + }}$$ can act as an oxidising agent.
Which of the above is/are true?
A
(i) and (iii)
B
(ii) and (iii)
C
(ii) only
D
(i) and (ii)
Answer :
(ii) and (iii)
$$La{\left( {OH} \right)_3}$$ is most basic. Hence, (i) is wrong. (ii) is correct due to lanthanoid contraction. (iii) is correct because $$C{e^{4 + }}$$ tends to change to stable $$C{e^{3 + }}.$$
176.
Which one of the following ions has electronic configuration $$\left[ {Ar} \right]3{d^6}?$$
$$\left( {{\text{At}}{\text{. no}}{\text{.}}} \right.\,Mn = 25,Fe = 26,$$ $$\left. {Co = 27,Ni = 28} \right)$$
177.
Which of the following compounds is expected to be coloured?
A
$$A{g_2}S{O_4}$$
B
$$Cu{F_2}$$
C
$$Mg{F_2}$$
D
$$CuCI.$$
Answer :
$$Cu{F_2}$$
The electronic configurations of cations in the given
salts are $$A{g^ + }\left( {4{d^{10}}} \right),C{u^{2 + }}\left( {3{d^9}} \right),M{g^{2 + }}\left( {2{s^2},2{p^6}} \right),C{u^ + }\left( {3{d^{10}}} \right){\mkern 1mu} {\mkern 1mu} {\text{only}}{\mkern 1mu} {\mkern 1mu} C{u^{2 + }}$$
ion has one unpaired electron in $${3d}$$ orbital and so, its salt is expected to be coloured.
178.
In an acidified aqueous solution of $$M{n^{2 + }},N{i^{2 + }},C{u^{2 + }}$$ and $$H{g^{2 + }}$$ ions, $${H_2}S$$ gas was passed. Precipitates are
A
$$MnS\,\,{\text{and}}\,\,CuS$$
B
$$NiS\,\,{\text{and}}\,\,HgS$$
C
$$MnS\,\,{\text{and}}\,\,NiS$$
D
$$CuS\,\,{\text{and}}\,\,HgS$$
Answer :
$$CuS\,\,{\text{and}}\,\,HgS$$
Group II cations are precipitated when $${H_2}S$$ gas is passed through their acidified aqueous solutions.
179.
Which one of the following exhibits the large number of oxidation states ?
A
$$Ti\left( {22} \right)$$
B
$$V\left( {23} \right)$$
C
$$Cr\left( {24} \right)$$
D
$$Mn\left( {25} \right)$$
Answer :
$$Mn\left( {25} \right)$$
Manganese exhibits the large number of oxidation states. The most common
oxidation states of $$Mn$$ are $$+2, +3, + 4, + 6$$ and $$+7.$$
180.
If $$M$$ is the element of actinoid series, the degree of complex formation decrease in the order
The higher the charge on the metal ion, smaller is the ionic size and more is the complex forming ability. Thus, the degree of complex formation decreases in the order : $${M^{4 + }} > MO_2^{2 + } > {M^{3 + }} > MO_2^ + $$
The higher tendency of complex formation of $$MO_2^{2 + }$$ as compared of $${M^{3 + }}$$ is due to high concentration of charge on metal atom $$M$$ in $$MO_2^{2 + }.$$