Classification of Elements and Periodicity in Properties MCQ Questions & Answers in Inorganic Chemistry | Chemistry
Learn Classification of Elements and Periodicity in Properties MCQ questions & answers in Inorganic Chemistry are available for students perparing for IIT-JEE, NEET, Engineering and Medical Enternace exam.
141.
Atomic numbers of few elements are given below. Which of the pairs belongs to $$s$$ - block?
142.
Which of the following arrangements represents the increasing order ( smallest to largest ) of ionic radii of the given species $${O^{2 - }},{S^{2 - }},{N^{3 - }},{P^{3 - }}?$$
For isoelectronic species ionic radii decreases as the charge on ion decreases. Further on moving down in a group ionic radii increases. Hence the correct order is $${O^{2 - }} < {N^{3 - }} < {S^{2 - }} < {P^{3 - }}$$
143.
Among halogens, the correct order of amount of energy released in electron gain ( electron gain enthalpy ) is
A
$$F > Cl > Br > I$$
B
$$F < Cl < Br < I$$
C
$$F < Cl > Br > I$$
D
$$F < Cl < Br > I$$
Answer :
$$F < Cl > Br > I$$
Electron gain enthalpy becomes less negative on moving down a group due to increase in atomic size. However, the electron gain enthalpy of $$F$$ is less negative than that of $$Cl$$ due to electron-electron repulsion in small sized $$F$$ atom. Thus, the correct order is :
\[\underset{{{\Delta }_{eg}}H\left( kJ\,\,mo{{l}^{-1}} \right)\,:}{\mathop{{}}}\,\,\,\underset{\begin{smallmatrix}
\\
-328
\end{smallmatrix}}{\mathop{F}}\,<\underset{\begin{smallmatrix}
\\
-349
\end{smallmatrix}}{\mathop{Cl}}\,>\underset{\begin{smallmatrix}
\\
-325
\end{smallmatrix}}{\mathop{Br}}\,>\underset{\begin{smallmatrix}
\\
-295
\end{smallmatrix}}{\mathop{I}}\,\]
144.
What is the correct order of electronegativity ?
Higher the positive charge the greater is the $$EN$$ and higher the negative charge the lesser is the $$EN.$$ So, $$EN$$ order is
$${M^ - } > {M^{2 - }} > {M^{3 - }} > {M^{4 - }}$$
145.
Why do noble gases have positive electron gain enthalpy?
A
It is difficult to add an electron due to small size.
B
It is difficult to add an electron due to high electronegativity.
C
It is difficult to add an electron due to stable configuration.
D
It is difficult to add an electron due to high electron affinity.
Answer :
It is difficult to add an electron due to stable configuration.
Due to stable configuration they do not accept an electron and hence they have positive electron gain enthalpy.
146.
Which is the most electropositive element?
A
$$Na$$
B
$$Cu$$
C
$$Cs$$
D
$$Ca$$
Answer :
$$Cs$$
The element that belongs to group 1 is the most electropositive. Electropositive character increases down the group.
147.
Correct order of first $$IP$$ 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 :
$$B < Be < C < O < N$$
$$Be - 1{s^2}2{s^2};B - 1{s^2}2{s^2}2{p^1};C - 1{s^2}2{s^2}2{p^2};$$ $$N - 1{s^2}2{s^2}2{p^3};O - 1{s^2}2{s^2}2{p^4}.\,\,IP$$ increases along the period. But $$IP$$ of $$Be > B.$$ Further $$IP$$ of $$O < N$$ because atoms with fully or partly filled orbitals are most stable and hence have high ionisation energy.
148.
Amongst the following elements (whose electronic configurations are given below), the one having the highest ionization energy is :
A
$$\left[ {Ne} \right]3{s^2}3{p^1}$$
B
$$\left[ {Ne} \right]3{s^2}3{p^3}$$
C
$$\left[ {Ne} \right]3{s^2}3{p^2}$$
D
$$\left[ {Ne} \right]3{d^{10}}4{s^2}4{p^3}$$
Answer :
$$\left[ {Ne} \right]3{s^2}3{p^3}$$
NOTE : Ionisation energy increases with increasing atomic number in a period, while it decreases on moving down a groups. $$IE$$ of element with electronic configuration (D) is lowest because of its biggest size. Among the remaining three elements of the same period $$\left( {3{\text{rd}}} \right).$$ $$IE$$ of element with electronic configuration (B) is the highest due to greater stability of the exactly half-filled $$3p$$ -subshell
149.
Elements $$X, Y$$ and $$Z$$ have atomic numbers 19, 37 and 55 respectively. Which of the following statements is true about them?
A
Their ionization potential would increase with increasing atomic number.
B
$$Y$$ would have an ionization potential between those of $$X$$ and $$Z.$$
C
$$Z$$ would have the highest ionization potential.
D
$$Y$$ would have the highest ionization potential.
Answer :
$$Y$$ would have an ionization potential between those of $$X$$ and $$Z.$$
Elements $$X, Y$$ and $$Z$$ with atomic numbers 19, 37, 55 lie in group 1 ( alkali metals ). Within a group, $$IE$$ decreases from top to bottom. Therefore, $$IE$$ of $$Y$$ could be between those of $$X$$ and $$Z.$$
150.
An element of atomic weight 40 has 2, 8, 8, 2 as the electronic configuration. Which one of the following statements regarding this element is not correct?
A
it belongs to II group of the periodic table
B
it has 20 neutrons
C
the formula of its oxide is $$M{O_2}$$
D
it belongs to 4th period of the periodic table
Answer :
the formula of its oxide is $$M{O_2}$$
Its valency is $$2.$$ So it will form $$MO$$ type compound.