Classification of Elements and Periodicity in Properties MCQ Questions & Answers in Inorganic Chemistry | Chemistry
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1.
Law of octaves stated,
A
every eighth element had properties similar to the first element
B
every third element had properties similar to the first element
C
the properties of the middle element were in between the other two members
D
the properties of the elements were repeated after regular intervals of 3, 4 or 8 elements
Answer :
every eighth element had properties similar to the first element
The law states that when lighter elements are arranged in order of their increasing atomic weights, the properties of every eighth element were similar to those of the first one like the eighth note of a musical scale.
2.
When we go from left to right in a period,
A
the basic nature of the oxides increases
B
the basic nature of the oxides decreases
C
there is no regular trend in the nature of oxides
D
oxides of only last two groups are basic in nature
Answer :
the basic nature of the oxides decreases
The basic nature of the oxides decreases from left to right in a period. e.g., in third period,
$$\mathop {N{a_2}O}\limits_{{\text{Strongly basic}}} > \mathop {MgO}\limits_{{\text{Basic}}} > \mathop {A{l_2}{O_3}}\limits_{{\text{Amphoteric}}} > $$ $$\mathop {Si{O_2}}\limits_{{\text{Weakly acidic}}} > \mathop {{P_4}{O_{10}}}\limits_{{\text{Acidic}}} > \mathop {S{O_2}}\limits_{{\text{Strongly}}\,\,{\text{acidic}}} $$ $$ > \mathop {C{l_2}{O_7}}\limits_{{\text{Strongly}}\,\,{\text{acidic}}} $$
3.
The first ionisation potential $$\left( {{\text{in}}\,\,eV} \right)$$ of $$Be$$ and $$B,$$ respectively are
A
8.29, 9.32
B
9.32, 9.32
C
8.29, 8.29
D
9.32, 8.29
Answer :
9.32, 8.29
First ionisation potential of beryllium $$(Be)$$ is greater than boron $$(B)$$ due to stable configuration
$${}_4Be = 1{s^2},2{s^2}$$
$${}_5B = 1{s^2},2{s^2}2{p^1}$$
Order of attraction of electrons towards nucleus is $$2s > 2p,$$ so more amount of energy is required to remove the electron from $$2s$$ orbital in comparison to $$2p$$ orbital. So, ionisation potential of $$Be$$ is 9.32 $$eV$$ and $$B$$ is 8.29 $$eV.$$
4.
According to the law of triads,
A
the properties of the middle element were in between those of the other two members
B
three elements arranged according to increasing weights have similar properties
C
the elements can be grouped in the groups of six elements
D
every third element resembles the first element in periodic table
Answer :
the properties of the middle element were in between those of the other two members
No explanation is given for this question. Let's discuss the answer together.
5.
An element with atomic number 117 is known as
A
Nihonium
B
Flerovium
C
Tennessine
D
Roentgenium
Answer :
Tennessine
Official name of an element with atomic number 117 is Tennessine $$(Ts)$$ given by IUPAC.
6.
Sum of first three ionization energies of $$Al$$ is $$53.0\,eV\,ato{m^{ - 1}}$$ and the sum of first two ionization energies of $$Na$$ is $$52.2\,eV\,ato{m^{ - 1}}.$$ Out of $$Al\left( {{\text{III}}} \right)$$ and $$Na\left( {{\text{II}}} \right)$$
A
$$Na\left( {{\text{II}}} \right)$$ is more stable than $$Al\left( {{\text{III}}} \right)$$
B
$$Al\left( {{\text{III}}} \right)$$ is more stable than $$Na\left( {{\text{II}}} \right)$$
C
Both are equally stable
D
Both are equally unstable
Answer :
$$Al\left( {{\text{III}}} \right)$$ is more stable than $$Na\left( {{\text{II}}} \right)$$
Ionization energy is not the only the criteria for the stability of an oxidation state.
7.
Electropositive or metallic character
A
increases along a period
B
decreases down a group
C
decreases along a period and increases down a group
D
of an element is reflected in its tendency to form covalent compounds
Answer :
decreases along a period and increases down a group
No explanation is given for this question. Let's discuss the answer together.
8.
Electronic configuration of four elements is given below. Which of the following does not belong to the same group?
A
$$\left[ {Kr} \right]4{d^{10}}5{s^2}$$
B
$$\left[ {Ar} \right]3{d^{10}}4{s^2}$$
C
$$\left[ {Xe} \right]4{f^{14}}5{d^{10}}6{s^2}$$
D
$$\left[ {Ar} \right]4{s^2}$$
Answer :
$$\left[ {Ar} \right]4{s^2}$$
No explanation is given for this question. Let's discuss the answer together.
9.
The main reason for showing anomalous properties of the first member of a group in $$s$$ or $$p$$ - block is
A
maximum chemical reactivity
B
maximum electronegativity and different configurations
C
small size, large charge/radius ratio
D
tendency to form multiple bonds
Answer :
small size, large charge/radius ratio
Due to small size, large charge/radius ratio and high electronegativity, the first element shows anomalous behaviour.
10.
Correct order of Ist ionisation potential $$(IP)$$ among following elements $$Be, B, C, N, O$$ is
A
$$B < Be < C < O < N$$
B
$$B < Be < C < N < O$$
C
$$Be < B < C < N < O$$
D
$$Be < B < C < O < N$$
Answer :
$$B < Be < C < O < N$$
An atom has electronic configuration
$$1{s^2},2{s^2},2{p^6}\,3{s^2}3{p^6}3{d^3},4{s^2}$$
It is a member of $$d$$- block element because the last electron is filled in $$d$$- subshell as $$3{d^3}$$ and the following electronic configuration is possible for $$d$$-subshell as $$\left( {n - 1} \right){d^{\left( {1\,to\,10} \right)}}$$
\[\underset{\begin{smallmatrix}
\\
\\
n{{s}^{2}}\left( n-1 \right){{s}^{2}}{{p}^{6}}
\end{smallmatrix}}{\mathop{\text{Group}\,\,\text{number}}}\,\,\,\,\,\,\underset{\begin{smallmatrix}
3 \\
{{d}^{1}}
\end{smallmatrix}}{\mathop{\text{III}\,B}}\,\,\,\underset{\begin{smallmatrix}
4 \\
{{d}^{2}}
\end{smallmatrix}}{\mathop{\,\,\,\text{IV}B}}\,\] \[\underset{\begin{smallmatrix}
5 \\
{{d}^{3}}
\end{smallmatrix}}{\mathop{\text{V}B}}\,\,\,\,\,\,\underset{\begin{smallmatrix}
6 \\
{{d}^{4}}
\end{smallmatrix}}{\mathop{\text{VI}\,B}}\,\,\,\,\,\,\underset{\begin{smallmatrix}
7 \\
{{d}^{5}}
\end{smallmatrix}}{\mathop{\text{VII}\,B\,\,}}\,\,\,\,\underset{\begin{smallmatrix}
8 \\
{{d}^{6}}
\end{smallmatrix}}{\mathop{\text{VIII}}}\,\] \[\underset{\begin{smallmatrix}
9 \\
{{d}^{7}}
\end{smallmatrix}}{\mathop{\text{VIII}}}\,\,\,\,\,\,\underset{\begin{smallmatrix}
10 \\
{{d}^{8}}
\end{smallmatrix}}{\mathop{\text{VIII}}}\,\,\,\,\,\,\underset{\begin{smallmatrix}
11 \\
{{d}^{9}}
\end{smallmatrix}}{\mathop{\text{IB}}}\,\,\,\,\,\,\underset{\begin{smallmatrix}
12 \\
{{d}^{10}}
\end{smallmatrix}}{\mathop{\text{IIB}}}\,\]
Hence, it is member of third group