Periodic Classification of Elements Test

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Periodic Classification of Elements Test - 3

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Weekly Quiz Competition

Question 1
1 / -0

In their attempts to classify the elements, which among the following scientists attempted to arrange them on the basis of similarity in properties alone?

A
Newlands

B
Dobereiner

C
Mendeleev

D
Moseley

Solution

Dobereiner selected his triads purely on the basis of similarity in properties.
Question 2
1 / -0

A, B and C are the elements of a Dobereiner's triad. If the atomic mass of A is 7 u and that of C is 39 u, what should be the atomic mass of B?

A
23 u

B
32 u

C
46 u

D
17 u

Solution

In Dobereiner's triads, the mass of the middle element is the average of the atomic masses of the other two elements.
Hence, atomic mass of B = = 23 u.
Question 3
1 / -0

According to Newlands law of octaves, beryllium resembles which of the following elements?

A
Sodium

B
Magnesium

C
Calcium

D
Aluminium

Solution

When arranged in the increasing order of atomic masses, magnesium is the eighth element after beryllium; and thus, the two elements have similar properties.
Question 4
1 / -0

Which of the following laws was formulated by Mendeleev?

A
The properties of elements are the periodic functions of their atomic radii.

B
The properties of elements are the periodic functions of their atomic numbers.

C
The properties of elements are the periodic functions of their atomic masses.

D
The properties of elements are the periodic functions of the number of neutrons in their nuclei.

Solution

All of the earlier attempts at classification were based on the assumption that atomic mass of the elements is the fundamental property that decides the chemical behaviour of the elements; until Moseley pointed out that the atomic number of the elements is a more basic property.
Question 5
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Lithium and sodium are placed in the same group of the Mendeleev's periodic table. Which of the following statements is/are the correct conclusion(s) drawn with regard to lithium and sodium?

(i) They have the same electronic configuration.
(ii) The formulae of their hydrides are the same.
(iii) The formulae of their oxides are the same.

A
(i) and (ii) only

B
(i) only

C
(iii) only

D
(ii) and (iii) only

Solution

Though Mendeleev gave the periodic law, which states that the properties of elements are periodic functions of their atomic masses, he gave priority to the similarity in the formulae of oxides and hydrides. He proposed that the elements with similar formulae of oxides and hydrides will show resemblance in all their properties.
Question 6
1 / -0

In which of the following pairs does the second element have a lesser electron affinity than the first?

A
Br, Cl

B
Cl, F

C
N, O

D
P, S

Solution

Electron affinity of an element is the tendency to gain an electron and form an anion.
Electron affinity increases across the period and decreases down the group.
Even though fluorine is more electronegative than chlorine, the latter has a greater electron affinity and can form anions more readily as being bigger in size it can adjust the incoming electron more easily.
In case of fluorine, repulsions come into play owing to its small size.
Question 7
1 / -0

Identify the incorrect statement about the ionisation energy.

A
It is the minimum energy required to remove the valence electron from outer most shell of an independent gaseous atom.

B
The alkali metals have the least ionisation energy in the respective period.

C
Ionisation of an atom is an exothermic process.

D
The value of ionisation energy decreases down the group.

Solution

Ionisation of an atom is an endothermic process, as energy is used to overcome the nuclear pull on the atom.
Question 8
1 / -0

An element with atomic number 10 belongs to:

A
Group: 18, Period: II

B
Group: 2, Period: II

C
Group: 8, Period: I

D
Group: 10, Period: III

Solution

Z = 10
Electronic configuration: 2,8
The element is Neon.
Since, there are two shells filled, it belongs to the period II.
As there are eight valence electrons, the group number is 8 + 10 = 18.
Question 9
1 / -0

The existence of which of the following present day elements was predicted by Mendeleev and was named Eka Boron?

A
Scandium

B
Gallium

C
Silicon

D
Germanium

Solution

Scandium is the present day element that was named Eka Boron, and Mendeleev not only predicted its existence, but also its position in his periodic table.
Question 10
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Which of the following pairs correctly represents the respective general formulae of oxides and hydrides made by all the elements of carbon group, as suggested by Mendeleev?

A
R₂O, RH

B
RO₂, RH₄

C
RO, RH₂

D
RO, RH₄

Solution

Mendeleev grouped together the elements having similar formulae of oxides and hydrides. The general formulae of oxides and hydrides of all elements of the carbon group are RO₂ and RH₄, respectively.
For example: CO₂, SiO₂
CH₄, SiH₄
Question 11
1 / -0

The numbers of groups in the s-block and p-block of the periodic table, respectively, are

A
10 and 6

B
6 and 2

C
2 and 6

D
2 and 10

Solution

There exists a correlation between the periodic table and the electronic configuration.
The s-block of the periodic table comprises elements in which the last electron enters the s-subshell. The s-subshell can accommodate 2 electrons and the s-block of the periodic table has 2 groups.
The p-block of the periodic table comprises elements in which the last electron enters the p-subshell. The p-subshell can accommodate 6 electrons and the p-block of the periodic table has 6 groups.

Question 12

1 / -0

The elements with atomic numbers 4, 12, 20, 38 and 56 belong to

alkali metals

alkaline earth metals

halogen group

noble gases

Solution

These are the atomic numbers of group 2 elements, known as the alkaline earth metals.

Element	Atomic number
Beryllium	4
Magnesium	12
Calcium	20
Strontium	38
Barium	56

Question 13

1 / -0

The most metallic element in group 15 (nitrogen family) is

Group 15

P

N

Bi

Sb

Solution

The metallic character (electropositive character) in elements increases down the group on account of the increase in atomic radius and the decrease in ionisation energy.

Question 14
1 / -0

Observe the elements of period III and select the strongest reducing and oxidising agents, respectively.

Na, Mg, Al, Si, P, S, Cl, Ar

A
Na and Mg

B
S and Cl

C
Na and Cl

D
Al and Si

Solution

Among the options, Na is the most electropositive element and is the strongest reducing agent; and Cl is the most electronegative element and is the strongest oxidising agent.
Question 15
1 / -0

Select the pair of amphoteric oxides from the following:

A
Na₂O and CaO

B
ZnO and AI₂O₃

C
P₂O₅ and SO₂

D
SIO₂ and CI₂O

Solution

Metallic oxides are basic in nature. For example, Na₂O and CaO.
Non-metallic oxides are acidic in nature. For example, P₂O₅, SO₂, SiO₂ and CI₂O.
Oxides of some metals are amphoteric, and can neutralise both acids and bases.
Example:
ZnO + 2HCI ZnCI₂ + H₂O
ZnO + 2NaOH Na₂ZnO₂ + H₂O
AI₂O₃ + 6HCI 2AICI₃ + 3H₂O
AI₂O₃ + 2NaOH 2NaAIO₂ + H₂O
Question 16
1 / -0

Which among the following is the smallest in size?

A
N³⁻

B
O^2-

C
F^-

D
Na⁺

Solution

Na⁺ will have the smallest ionic radius because 10 electrons are held by 11 protons in the nucleus.
Question 17
1 / -0

Which of the following is not correct about the modern periodic table?

A
The elements in a period have the same number of shells.

B
The outermost electron of the elements in a period have the same Azimuthal quantum number.

C
The number of shells occupied increase regularly down a group.

D
The effective nuclear charge increases across a period.

Solution

The Azimuthal quantum number changes across a period.
e.g. Period III has portions of the s-block (groups 1 & 2), d-block (groups 3 to 12), p-block (groups 13 to 18)
l = 0 in the s-block, l = 2 in the d-block, and l = 1 in the p-block.

Question 18

1 / -0

Elements A, B and C have positions in the periodic table as shown below:

Group 16	Group 17
--------	--------
--------	A
--------	--------
B	C

(i) A is a metal.
(ii) C is smaller in size as compared to B.
(iii) Element A forms a negatively charged ion.

Which of the above statements is/are correct?

All (i), (ii) and (iii)

Only (ii) and (iii)

Only (ii)

Only (i) and (iii)

Solution

A belongs to group 17, and is a non-metal; hence, statement (i) is incorrect.
C is smaller in size than B because the atomic radius decreases across the period.
A is electronegative and will form anions by gaining electrons.
Thus, option (2) is correct.

Question 19
1 / -0

The bond in the compounds formed by the combination of group 14 and group 17 elements of the periodic table will be a/an

A
electrovalent bond

B
co-ordinate bond

C
Van der Waals bond

D
covalent bond

Solution

The elements of group 14 and group 17 are non-metallic and they bond by sharing electrons; hence, they are covalent compounds.
Question 20
1 / -0

An element A belongs to third period and second group of the periodic table. The number of valence electrons of element A is

A
one

B
two

C
three

D
four

Solution

The element is Mg.
Each element of group 2 (group of alkaline earth metals) has 2 valence electrons.

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Periodic Classification of Elements Test - 3

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Question 1

Newlands

Dobereiner

Mendeleev

Moseley

Solution

Question 2

23 u

32 u

46 u

17 u

Solution

Question 3

Sodium

Magnesium

Calcium

Aluminium

Solution

Question 4

The properties of elements are the periodic functions of their atomic radii.

The properties of elements are the periodic functions of their atomic numbers.

The properties of elements are the periodic functions of their atomic masses.

The properties of elements are the periodic functions of the number of neutrons in their nuclei.

Solution

Question 5

(i) and (ii) only

(i) only

(iii) only

(ii) and (iii) only

Solution

Question 6

Br, Cl

Cl, F

N, O

P, S

Solution

Question 7

It is the minimum energy required to remove the valence electron from outer most shell of an independent gaseous atom.

The alkali metals have the least ionisation energy in the respective period.

Ionisation of an atom is an exothermic process.

The value of ionisation energy decreases down the group.

Solution

Question 8

Group: 18, Period: II

Group: 2, Period: II

Group: 8, Period: I

Group: 10, Period: III

Solution

Question 9

Scandium

Gallium

Silicon

Germanium

Solution

Question 10

R2O, RH

RO2, RH4

RO, RH2

RO, RH4

Solution

Question 11

10 and 6

6 and 2

2 and 6

2 and 10

Solution

Question 12

alkali metals

alkaline earth metals

halogen group

noble gases

Solution

R₂O, RH

RO₂, RH₄

RO, RH₂

RO, RH₄

Na₂O and CaO

ZnO and AI₂O₃

P₂O₅ and SO₂

SIO₂ and CI₂O

N³⁻

O^2-

F^-

Na⁺