Classification of Elements & Periodicity Practice Questions - DPP for NEET

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1. (d) All the given species contains 10 e
–
 each i.e. isoelectronic.
For isoelectronic species anion having high negative charge is largest  in
size and the cation having high positive charge is smallest.
2. (c) All the given species are isoelectronic. In case of isoelectronic
species ionic radii increases with increase in negative charge on
anions.
3. (b) On moving along the period, ionization enthalpy increases.
In second period, the order of ionization enthalpy should be as follows :
F > O > N.
But N has half-filled structure, therefore, it is more stable than O. That is
why its ionization enthalpy is higher than O. Thus, the correct order
of IE is
F > N > O.
4. (c) In a period the value of ionisation potential increases from left to
right with breaks where the atoms have some what stable
configuration. In this case N has half filled stable orbitals. Hence
has highest ionisation energy. Thus the correct order is B < C < O <
N and not as given in option (c)
5. (b) The acidic character of non metal oxides increases across a period
from left to right and decreases down a group. So, acidic character
will follow the order:
oxide of nitrogen > oxides of sulfur > oxides of carbon.
Among oxides of carbon acidic character increases with the oxidation
number of carbon. So,  is more acidic than CO. Hence the
sequence of acidic character is N
2
O
5
 > SO
2
 > CO
2
 > CO
6. (b) Along the period, I.P. generally increases but not regularly. Be and
B are exceptions. First I.P. increases in moving from left to right in
a period, but I.P. of B is lower than Be.
7. (b) IE
2
 of Mg is lower than that of Na because in case of Mg
+
, 3s-
electron has to be removed whereas in case of Na
+
, an electron is
removed from the stable inert gas configuration which is difficult.
8. (b) According to modern periodic law, the properties of the elements
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1. (d) All the given species contains 10 e
–
 each i.e. isoelectronic.
For isoelectronic species anion having high negative charge is largest  in
size and the cation having high positive charge is smallest.
2. (c) All the given species are isoelectronic. In case of isoelectronic
species ionic radii increases with increase in negative charge on
anions.
3. (b) On moving along the period, ionization enthalpy increases.
In second period, the order of ionization enthalpy should be as follows :
F > O > N.
But N has half-filled structure, therefore, it is more stable than O. That is
why its ionization enthalpy is higher than O. Thus, the correct order
of IE is
F > N > O.
4. (c) In a period the value of ionisation potential increases from left to
right with breaks where the atoms have some what stable
configuration. In this case N has half filled stable orbitals. Hence
has highest ionisation energy. Thus the correct order is B < C < O <
N and not as given in option (c)
5. (b) The acidic character of non metal oxides increases across a period
from left to right and decreases down a group. So, acidic character
will follow the order:
oxide of nitrogen > oxides of sulfur > oxides of carbon.
Among oxides of carbon acidic character increases with the oxidation
number of carbon. So,  is more acidic than CO. Hence the
sequence of acidic character is N
2
O
5
 > SO
2
 > CO
2
 > CO
6. (b) Along the period, I.P. generally increases but not regularly. Be and
B are exceptions. First I.P. increases in moving from left to right in
a period, but I.P. of B is lower than Be.
7. (b) IE
2
 of Mg is lower than that of Na because in case of Mg
+
, 3s-
electron has to be removed whereas in case of Na
+
, an electron is
removed from the stable inert gas configuration which is difficult.
8. (b) According to modern periodic law, the properties of the elements
are repeated after certain regular intervals when these elements are
arranged in order of their increasing atomic numbers.
9. (a) For isoelectronic species, size of anion increases as negative charge
increases whereas size of cation decreases with increase in positive
charge. Further ionic radii of anions is more than that of cations.
Thus the correct order is       Ca
++ 
< K
+
 < Ar < Cl
–
 < S
– –
10. (b) The alkali metals are highly reactive because their first ionisation
potential is very low and hence they have great tendency to loses
electron to form unipositive ion.
On moving down group- I from Li to Cs ionisation enthalpy decreases
hence the reactivity increases. The halogens are most reactive
elements due to their low bond dissociation energy, high electron
affinity and high enthalpy of hydration of halide ion. However their
reactivity decreases with increase in atomic number
11. (b) In hydrides of 15th group elements, basic character decreases on
descending the group i.e.
NH
3
 > PH
3
 > AsH
3
 > SbH
3
.
12. (b) The right sequence of I.E
1
 of  Li < B < Be < C.
13. (a) As the nuclear charge increases, the force of attraction between the
nucleus and the incoming electron increases and hence the elecron
gain enthalpy becomes more negative, hence the correct order is
Ca   <   Al    <   C    <   O   <    F
14. (a) First period has H and He only out of which He is inert, hence, H
behaves as a highly electropositive as well as electronegative.
15. (d) As the size increases the basic nature of oxides changes to acidic
nature i.e., acidic nature increases.
SO
2
 and P
2
O
3
 are acidic as their corresponding acids H
2
SO
3
 and H
3
PO
3
are strong acids.
16. (a) 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–
17. (a) Incoming electrons occupies the smaller n = 2 shell, also negative
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1. (d) All the given species contains 10 e
–
 each i.e. isoelectronic.
For isoelectronic species anion having high negative charge is largest  in
size and the cation having high positive charge is smallest.
2. (c) All the given species are isoelectronic. In case of isoelectronic
species ionic radii increases with increase in negative charge on
anions.
3. (b) On moving along the period, ionization enthalpy increases.
In second period, the order of ionization enthalpy should be as follows :
F > O > N.
But N has half-filled structure, therefore, it is more stable than O. That is
why its ionization enthalpy is higher than O. Thus, the correct order
of IE is
F > N > O.
4. (c) In a period the value of ionisation potential increases from left to
right with breaks where the atoms have some what stable
configuration. In this case N has half filled stable orbitals. Hence
has highest ionisation energy. Thus the correct order is B < C < O <
N and not as given in option (c)
5. (b) The acidic character of non metal oxides increases across a period
from left to right and decreases down a group. So, acidic character
will follow the order:
oxide of nitrogen > oxides of sulfur > oxides of carbon.
Among oxides of carbon acidic character increases with the oxidation
number of carbon. So,  is more acidic than CO. Hence the
sequence of acidic character is N
2
O
5
 > SO
2
 > CO
2
 > CO
6. (b) Along the period, I.P. generally increases but not regularly. Be and
B are exceptions. First I.P. increases in moving from left to right in
a period, but I.P. of B is lower than Be.
7. (b) IE
2
 of Mg is lower than that of Na because in case of Mg
+
, 3s-
electron has to be removed whereas in case of Na
+
, an electron is
removed from the stable inert gas configuration which is difficult.
8. (b) According to modern periodic law, the properties of the elements
are repeated after certain regular intervals when these elements are
arranged in order of their increasing atomic numbers.
9. (a) For isoelectronic species, size of anion increases as negative charge
increases whereas size of cation decreases with increase in positive
charge. Further ionic radii of anions is more than that of cations.
Thus the correct order is       Ca
++ 
< K
+
 < Ar < Cl
–
 < S
– –
10. (b) The alkali metals are highly reactive because their first ionisation
potential is very low and hence they have great tendency to loses
electron to form unipositive ion.
On moving down group- I from Li to Cs ionisation enthalpy decreases
hence the reactivity increases. The halogens are most reactive
elements due to their low bond dissociation energy, high electron
affinity and high enthalpy of hydration of halide ion. However their
reactivity decreases with increase in atomic number
11. (b) In hydrides of 15th group elements, basic character decreases on
descending the group i.e.
NH
3
 > PH
3
 > AsH
3
 > SbH
3
.
12. (b) The right sequence of I.E
1
 of  Li < B < Be < C.
13. (a) As the nuclear charge increases, the force of attraction between the
nucleus and the incoming electron increases and hence the elecron
gain enthalpy becomes more negative, hence the correct order is
Ca   <   Al    <   C    <   O   <    F
14. (a) First period has H and He only out of which He is inert, hence, H
behaves as a highly electropositive as well as electronegative.
15. (d) As the size increases the basic nature of oxides changes to acidic
nature i.e., acidic nature increases.
SO
2
 and P
2
O
3
 are acidic as their corresponding acids H
2
SO
3
 and H
3
PO
3
are strong acids.
16. (a) 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–
17. (a) Incoming electrons occupies the smaller n = 2 shell, also negative
Helium (He) 1s
2
? Highest ionisation
energy due to noble gas
in nature.
Fluorine (F) 1s
2
 2s
2
2p
3
? High electronegativity in
nature due to small size
and –1 oxidation state.
Rubidium (Rb) ? Most electronegative
element due to large
atomic size.
Lithium (Li) ? Strongest reducing agent
due to small size and
positive oxidation state
(+1)
charge on oxygen (O
–
) is another factor due to which incoming
electron feel repulsion.
Hence electron repulsion outweigh the stability gained by achieving
noble gas configuration.
18. (b) In the isoelectronic species, all isoelectronic anions belong to the
same period and cations to the next period.
19. (d)
20. (d)
21. (147)  Van der Waal radii is one-half of the distance between the nuclei
of two identical non-bonded isolated atoms. These atoms are
attracted toward each other through weak van der Waal’s force
hence van der Waal radii are very large.
22. (120) Atomic number of Unbinilium (Ubn) is 120
23. (17) As we move down in a group electron gain enthalpy becomes less
negative because the size of the atom increases and the distance of
added electron from the nucleus increases. Negative electron gain
enthalpy of F is less than Cl. This is due to the fact that when an
electron is added to F, the added electron goes to the smaller n = 2
energy level and experiences significant repulsion from the other
electrons present in this level. In Cl, the electron goes to the larger
n = 3 energy level and consequently occupies a larger region of
space leading to much less electron–electron repulsion. So the
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1. (d) All the given species contains 10 e
–
 each i.e. isoelectronic.
For isoelectronic species anion having high negative charge is largest  in
size and the cation having high positive charge is smallest.
2. (c) All the given species are isoelectronic. In case of isoelectronic
species ionic radii increases with increase in negative charge on
anions.
3. (b) On moving along the period, ionization enthalpy increases.
In second period, the order of ionization enthalpy should be as follows :
F > O > N.
But N has half-filled structure, therefore, it is more stable than O. That is
why its ionization enthalpy is higher than O. Thus, the correct order
of IE is
F > N > O.
4. (c) In a period the value of ionisation potential increases from left to
right with breaks where the atoms have some what stable
configuration. In this case N has half filled stable orbitals. Hence
has highest ionisation energy. Thus the correct order is B < C < O <
N and not as given in option (c)
5. (b) The acidic character of non metal oxides increases across a period
from left to right and decreases down a group. So, acidic character
will follow the order:
oxide of nitrogen > oxides of sulfur > oxides of carbon.
Among oxides of carbon acidic character increases with the oxidation
number of carbon. So,  is more acidic than CO. Hence the
sequence of acidic character is N
2
O
5
 > SO
2
 > CO
2
 > CO
6. (b) Along the period, I.P. generally increases but not regularly. Be and
B are exceptions. First I.P. increases in moving from left to right in
a period, but I.P. of B is lower than Be.
7. (b) IE
2
 of Mg is lower than that of Na because in case of Mg
+
, 3s-
electron has to be removed whereas in case of Na
+
, an electron is
removed from the stable inert gas configuration which is difficult.
8. (b) According to modern periodic law, the properties of the elements
are repeated after certain regular intervals when these elements are
arranged in order of their increasing atomic numbers.
9. (a) For isoelectronic species, size of anion increases as negative charge
increases whereas size of cation decreases with increase in positive
charge. Further ionic radii of anions is more than that of cations.
Thus the correct order is       Ca
++ 
< K
+
 < Ar < Cl
–
 < S
– –
10. (b) The alkali metals are highly reactive because their first ionisation
potential is very low and hence they have great tendency to loses
electron to form unipositive ion.
On moving down group- I from Li to Cs ionisation enthalpy decreases
hence the reactivity increases. The halogens are most reactive
elements due to their low bond dissociation energy, high electron
affinity and high enthalpy of hydration of halide ion. However their
reactivity decreases with increase in atomic number
11. (b) In hydrides of 15th group elements, basic character decreases on
descending the group i.e.
NH
3
 > PH
3
 > AsH
3
 > SbH
3
.
12. (b) The right sequence of I.E
1
 of  Li < B < Be < C.
13. (a) As the nuclear charge increases, the force of attraction between the
nucleus and the incoming electron increases and hence the elecron
gain enthalpy becomes more negative, hence the correct order is
Ca   <   Al    <   C    <   O   <    F
14. (a) First period has H and He only out of which He is inert, hence, H
behaves as a highly electropositive as well as electronegative.
15. (d) As the size increases the basic nature of oxides changes to acidic
nature i.e., acidic nature increases.
SO
2
 and P
2
O
3
 are acidic as their corresponding acids H
2
SO
3
 and H
3
PO
3
are strong acids.
16. (a) 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–
17. (a) Incoming electrons occupies the smaller n = 2 shell, also negative
Helium (He) 1s
2
? Highest ionisation
energy due to noble gas
in nature.
Fluorine (F) 1s
2
 2s
2
2p
3
? High electronegativity in
nature due to small size
and –1 oxidation state.
Rubidium (Rb) ? Most electronegative
element due to large
atomic size.
Lithium (Li) ? Strongest reducing agent
due to small size and
positive oxidation state
(+1)
charge on oxygen (O
–
) is another factor due to which incoming
electron feel repulsion.
Hence electron repulsion outweigh the stability gained by achieving
noble gas configuration.
18. (b) In the isoelectronic species, all isoelectronic anions belong to the
same period and cations to the next period.
19. (d)
20. (d)
21. (147)  Van der Waal radii is one-half of the distance between the nuclei
of two identical non-bonded isolated atoms. These atoms are
attracted toward each other through weak van der Waal’s force
hence van der Waal radii are very large.
22. (120) Atomic number of Unbinilium (Ubn) is 120
23. (17) As we move down in a group electron gain enthalpy becomes less
negative because the size of the atom increases and the distance of
added electron from the nucleus increases. Negative electron gain
enthalpy of F is less than Cl. This is due to the fact that when an
electron is added to F, the added electron goes to the smaller n = 2
energy level and experiences significant repulsion from the other
electrons present in this level. In Cl, the electron goes to the larger
n = 3 energy level and consequently occupies a larger region of
space leading to much less electron–electron repulsion. So the
correct order is  Cl > F > Br > I.
Atomic number of Cl is 17.
24. (5251) I represents Li, II represents K
III represents Br, IV represents I
V represents He
So, amongst these, V represents least reactive non-metal.
25. (3.06) Q Energy released for 10
6
 atoms = 4.9 × 10
–13
 J
? Energy released for 1 atom = 
= 
= 3.06 eV.