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.
61.
Among the elements with atomic numbers 9, 12, 16 and 36 which is highly electropositive?
A
Element with atomic number 9
B
Element with atomic number 12
C
Element with atomic number 16
D
Element with atomic number 36
Answer :
Element with atomic number 12
$$\eqalign{
& Z = 9;\,\,\,\,\,\,1{s^2}2{s^2}2{p^5} \cr
& Z = 12;\,\,\,\,1{s^2}2{s^2}2{p^6}3{s^2} \cr
& Z = 16;\,\,\,\,1{s^2}2{s^2}2{p^6}3{s^2}3{p^4} \cr
& Z = 36;\,\,\,\,1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}3{d^{10}}4{s^2}4{p^6} \cr} $$
Electropositivity decreases along the period while it increases going down the group.
62.
Which electronic configuration of an element has abnormally high difference between second and third ionisation energy?
A
$$1{s^2},2{s^2}2{p^6},3{s^1}$$
B
$$1{s^2},2{s^2}2{p^6},3{s^2}3{p^1}$$
C
$$1{s^2},2{s^2}2{p^6},3{s^2}3{p^2}$$
D
$$1{s^2},2{s^2}2{p^6},3{s^2}$$
Answer :
$$1{s^2},2{s^2}2{p^6},3{s^2}$$
When the element having $$1{s^2},2{s^2}2{p^6},3{s^2}$$ configuration, loss two electrons, then it acquire the electronic configuration of noble gas $$(Ne),$$ so to remove third electron a large amount of energy is required and hence, its second and third ionisation energy have large difference.
63.
Choose the incorrect statement.
A
Chemical reactivity tends to be high in group 1 metals, lower in elements in middle and increases to maximum in the group 17.
B
Halogens have very high negative electron gain enthalpy.
C
Noble gases have large positive electron gain enthalpy.
D
Decrease in electronegativities across a period is accompanied by an increase in non-metallic properties
Answer :
Decrease in electronegativities across a period is accompanied by an increase in non-metallic properties
Electronegativity increases across a period.
64.
What is the name and symbol of the element with atomic number 112?
A
Copernicium, $$Cn$$
B
Oganesson, $$Og$$
C
Dubnium, $$Db$$
D
Moscovium, $$Mc$$
Answer :
Copernicium, $$Cn$$
No explanation is given for this question. Let's discuss the answer together.
65.
Match the atomic numbers given in column I with the block in which the element is placed in column II and mark the appropriate choice.
Column I (Atomic number)
Column II (Block)
a.
62
1.
$$d$$-block
b.
47
2.
$$p$$-block
c.
56
3.
$$f$$-block
d.
53
4.
$$s$$-block
A
a - 3, b - 1, c - 4, d - 2
B
a - 1, b - 2, c - 3, d - 4
C
a - 2, b - 4, c - 1, d - 3
D
a - 4, b - 1, c - 2, d - 3
Answer :
a - 3, b - 1, c - 4, d - 2
No explanation is given for this question. Let's discuss the answer together.
66.
The first ionisation potential in electron volts of nitrogen and oxygen atoms are respectively given by
A
$$14.6,13.6\,$$
B
$$13.6,14.6$$
C
$$13.6,13.6$$
D
$$14.6,14.6$$
Answer :
$$14.6,13.6\,$$
Ionisation potential of nitrogen is more than that of oxygen. This is because nitrogen has more stable half-filled $$p$$-orbitals. $$\left( {N - 1{s^2},2{s^2},2{p^3},O = 1{s^2},2{s^2},2{p^4}} \right)$$
67.
Electron affinity is positive for
A
$$O\left( g \right) + {e^ - } \to {O^ - }\left( g \right)$$
B
$$S\left( g \right) + {e^ - } \to {S^ - }\left( g \right)$$
C
$${O^ + }\left( g \right) + {e^ - } \to O\left( g \right)$$
D
$${O^ - }\left( g \right) + {e^ - } \to {O^{2 - }}\left( g \right)$$
Answer :
$${O^ - }\left( g \right) + {e^ - } \to {O^{2 - }}\left( g \right)$$
$${O^ - }\,ion$$ repel the incoming electron thus energy is required to add incoming electron.
68.
The period to which an element belongs to in the long form of periodic table represents
A
atomic mass
B
atomic number
C
principal quantum number
D
azimuthal quantum number
Answer :
principal quantum number
$$n$$ is the principal quantum number or number of shells. It represents the number of period to which an element belongs to.
69.
The correct order of second ionisation potential of carbon, nitrogen, oxygen and fluorine is
A
$$C > N > O > F$$
B
$$O > N > F > C$$
C
$$O > F > N > C$$
D
$$F > O > N > C$$
Answer :
$$O > F > N > C$$
NOTE : Ionization potential is amount of energy required to take out most loosely bonded electron from neutral atom. Its value depends on stability of atom
(electronic configuration)
$$C - 1{s^2}2{s^2}{p^2}\,\,\,\,\,\,\,{C^ + } - 1{s^2}2{s^2}{p^1}$$
$$N - 1{s^2}2{s^2}{p^3}\,\,\,\,\,\,{N^ + } - 1{s^2}2{s^2}{p^2}$$
$$O - 1{s^2}2{s^2}{p^4}\,\,\,\,\,\,\,{O^ + } - 1{s^2}2{s^2}{p^3}$$
$$F - 1{s^2}2{s^2}{p^5}\,\,\,\,\,\,\,{F^ + } - \,1{s^2}2{s^2}{p^4}$$
$$\left( {{\text{for second ionisation potential, }}I{E_2}{\text{ }}} \right)$$
As for $$I{E_2}$$ the electron in all the cases is to be removed
from $$2p$$ orbital so it must follow the order
$$C < N < O < F$$ (i.e. increase across a period)
But in case of $${O^ + },$$ the $$2p$$ orbital is half-filled and is
more stable as compared to others. So the order becomes: $$C < N < F\, < O\,\,{\text{or}}\,O > F > N > C\,\,$$
70.
The first ionisation enthalpy of the elements $$C, N, P, Si$$ are in the order of
A
$$C < N < Si < P$$
B
$$N < Si < C < P$$
C
$$Si < P < C < N$$
D
$$P < Si < N < C$$
Answer :
$$Si < P < C < N$$
No explanation is given for this question. Let's discuss the answer together.