Evolution of Periodic Table ( 15+ Qs)[From NCERT]

Ruhul Amin Alig

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Classification of Elements and Periodicity in Properties>
Evolution of Periodic Table ( 12 Qs)

Question: From NCERT NEET Derived PYQ

According to Moseley, a straight-line graph is obtained on plotting-

1. The frequencies of characteristic X-rays of elements against their atomic numbers.

2. The square of the frequencies of characteristic X-rays of elements against their atomic numbers

3. The square root of the frequencies of characteristic X-rays of elements against their atomic numbers

4. The reciprocal of the frequencies of characteristic X-rays of elements against their atomic numbers.

Answer ▽

3. The square root of the frequencies of characteristic X-rays of elements against their atomic numbers

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Question: From NCERT NEET Derived PYQ

If a graph is plotted with the atomic number on x-axis and the square root of the frequency of a spectral line of characteristic X-rays on the y-axis, then it will be
A) A straight line passing through the origin
B) A parabola
C) A straight line not passing through the origin
D) A rectangular hyperbola

Answer ▽

C) A straight line not passing through the origin

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Question: From NCERT NEET Derived PYQ

The law of triads is applicable to a group of:

1. Cl, Br, I

2. C, N, O

3. Na, K, Rb

4. H, O, N

Answer ▽

1. Cl, Br, I

Only four triads were mentioned – (Li,Na,K + Ca,Sr,Ba + Cl,Br,I + S,Se,Te).

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Question: From NCERT NEET Derived PYQ

If atomic number of an element of He-family is Z then which of the following atomic number will highest EA?
(1) Z - 2
(2) Z - 1
(3) Z + 1
(4) Z + 2

Answer ▽

(2) Z - 1

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Question: From NCERT NEET Derived PYQ

Incorrect statement among the following is -

1. Van der Waals' radius of iodine is more than its covalent radius

2. All isoelectronic ions belong to the same period of the periodic table

3. $I . E_{1}$ of N is higher than that of O while $I . E_{2}$ of O is higher than that of N

4. The electron affinity N is almost zero while that of P is 74.3 kJ $m o l^{- 1}$

Answer ▽

2. All isoelectronic ions belong to the same period of the periodic table

All isoelectronic ions belong to the same period of the periodic table, is a wrong statement as $F^{-}$ and $N a^{+}$ are isoelectronic but they belong to different periods.
$I E_{1}$ of $N$ is higher than that of $O$ while $I E_{2}$ of $O$ is higher than that of $N$ due to stable half filled configuration.
Van der Waal's radius of iodine is more than its covalent radius.

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Question: From NCERT NEET Derived PYQ

Which of the following statements are correct?
I) The van der Waals radius is nearly 40% less than the covalent radius.
II) The atomic radius of neon is more than fluorine.
III) The decrease in atomic radius is more when second electron enters into s-subshell.
A
I and II
B
I and III
C
II and III
D
I, II and III

Answer ▽

Correct option is C)

A) The van der Waals radius is nearly 40% greater than the covalent radius, as it is measured in a non-bonding condition.

B) In a period, size decreases on going from left to right due to an increase in effective nuclear charge. Thus, alkali metals have large atomic radii and halogens have the smallest size.

The atomic radius of neon is greater than that of fluorine. Halogens have the smallest size in a particular period while noble gases have the largest size, as their van der Waals radius is measured, which is the largest.

C) When the second electron enters in s-subshell, the nucleus experiences a higher effective nuclear charge and there is more contraction in their size.

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Question: From NCERT NEET Derived PYQ

With reference to the diagram given, the van der Waals radius is equal to:

$A - A$

$B - A$

$B - D$

$A - C$

Medium

Answer ▽

Correct option is D)

With reference to the diagram given, the van der Walls radius is equal to A−C .

The van der Walls radius is one half of the distance between the nuclei of two non bonded adjacent atoms belonging to two neighbouirng molecules of an element in the solid state.

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Question: From NCERT NEET Derived PYQ

Consider the following statements:

(I) Rutherford name was associated with the development of periodic table.

(II) A metal M having electronic configuration $1 s^{2}, 2 s^{2}, 2 p^{6}, 3 s^{2}, 3 p^{6}, 3 d^{10}, 4 s^{1}$ is d-block element.

(III) Diamond is an element.

(IV) The electronic configuration of the most electronegative elements is $1 s^{2}, 2 s^{2}, 2 p^{5},$

and select the correct one from the given codes.

(A) I, II, IV (B) I, II, III, IV

Answer ▽

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Question: From NCERT NEET Derived PYQ

Assertion : The $5^{t h}$ period of periodic table contains 18 elements and not 32.

Reason : n = 5, –1 = 0, 1, 2, 3. The order in which the energy of available orbits 4d, 5s and 5p increases is 5s < 4d < 5p and the total number of orbitals available are 9 and thus 18 electrons can be accommodated.

If both the assertion and the reason are true and the reason is a correct explanation of the assertion
If both the assertion and reason are true but the reason is not a correct explanation of the assertion
If the assertion is true but the reason is false
If both the assertion and reason are false

Answer ▽

If both the assertion and the reason are true and the reason is a correct explanation of the assertion

In the fifth period, f orbitals are not filled.
Thus, both assertion and reason are correct and reason is the correct explanation for assertion.
For 5TH period, principal quantum number, n=5 and values of azimuthal quantum number, l=0, 1,2,3
According to Aufbau principle, filling of orbitals in subshells takes place in increasing order of energy of subshell .Since energy of 4f subshell is higher than 5s subshell, the sub shells available for filling are 5s, 4d, 5p.
Therefore, total number of orbitals =1 for 5s+ 5 for 4d + 3 for 5p
$= 1 + 5 + 3 = 9$ $= 1 + 5 + 3 = 9$
Therefore, total number of electrons that can be accommodated in 9 orbitals $= 2 x 9 = 18$ $= 2 x 9 = 18$
Hence, the number of electrons or elements in 5th period are 18.
5s<4d<5p

Additional information
-Principle quantum number
1.It is denoted by n
2.It tells us the main energy level or shell in which the electron may be present.
3.Its value can be an integer except zero.
4.The energy levels are also denoted by letters K, L , M, N ……
5.The energy of the various shells follow the sequence :

6.The total number of electrons present in any main shell is given by

-Azimuthal quantum number
1.It is also known as subsidiary or angular momentum quantum number
2.It is denotes by l
3.It arises from the explanation that electrons I main energy level do not have the same energy in case of a multi electron system. This is because the electrons move along different paths and hence have different angular momentum.
4.It tells us the number of subshells present within the main shell.
5.In general, we can say that the number of subshells present in any main shell is equal to the number of the main shell
6.Energy sequence is

s < p < d < f

Note:
Aufbau‘s principle-
It is also known as (n+l ) rule . According to this principle, during electron filling in an atom, the orbital having lowest energy is filled first followed by the orbitals of higher energy.

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Question: From NCERT NEET Derived PYQ

Which one of the following is different from the others with respect to valency?
A.Potassium
B.Ammonium
C.Barium
D.Lithium

Answer ▽

The combining capacity of an atom or molecule is measured by its valency. Elements belonging to the same group of the periodic table tend to have the same valency. It is related to the number of electrons present in the outer shell.

We can follow this following method in order to calculate valency of an element. Suppose, for a compound, the number of electrons in the outermost shell is between one to four, then the compound is said to have positive valency. On the other hand, for compounds having electrons four, five, six, or seven, the valency can be determined by subtracting the number of electrons from eight.

Optios-
The atomic number of Potassium is 19, with electronic configuration 2,8,8,1 .So, it needs to lose 1 electron in order to attain stability. Therefore, it has the valency of +1

Lithium has an atomic number of 3, having electronic configuration 2, 1. So, it needs to lose only one electron in order to achieve stable configuration. So, its valency will be 1.

Barium belongs to group II, and it has 2 electrons in its outermost shell, i.e., 6s shell. It can readily lose these 2 electrons in order to attain stability. So, barium has valency of 2.

Ammonium has the chemical formula of

${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$
${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ . Its valency is +1 most of the time, because it consists of one free electron on the central metal atom nitrogen.

So, the correct option is C.

${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$

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Question: From NCERT NEET Derived PYQ

Assertion : :The 4f- and 5f- inner transition series of elements are placed separately at
the bottom of the periodic table.

Reason : (i) This prevents the undue expansion of the periodic table i.e., maintains its structure.
(ii) This preserve the principle of classification by keeping elements with similar properties in a single column.

If both the assertion and the reason are true and the reason is a correct explanation of the assertion
If both the assertion and reason are true but the reason is not a correct explanation of the assertion
If the assertion is true but the reason is false
If both the assertion and reason are false

Answer ▽

If both the assertion and the reason are true and the reason is a correct explanation of the assertion

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Question: From NCERT NEET Derived PYQ

Eka– aluminium would form oxide with formula :

(1) ${EO}_{4}$

(2) $E_{2} O_{3}$

(3) $E_{3} O_{2}$

(4) EO

Answer ▽

(2)

Eka-Aluminium essentially means one after Aluminium, which is Gallium. Now we know the valency of Aluminium is 3, which will give us its oxidation state of +3. Since, Aluminium and Gallium belong to the same group their valency will also be the same which is 3. Hence, the same oxidation state. Every element desire to attain the noble gas configuration and it is easier for Gallium to lose 3 electrons rather than gaining 5 electrons. Now to form a neutral oxide, Gallium must form a compound.

Oxygen has 6 valence electrons, which gives it an oxidation state of -2. As it can gain two electrons to complete its noble gas configuration rather than losing 6 of its electrons.
As a result, 2 Ga will share its 6 electrons with 3 O atoms, which shares it 6 electrons and form the compound

,which is similar to

So, the correct option is (c).

$E_{2} O_{3}$

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Question: From NCERT NEET Derived PYQ

Which of the following ions is the smallest in size?
A) $C l^{-}$
B) $N a^{+}$
C) $M g^{2 +}$
D) $S_{2}^{-}$

Answer ▽

C) $M g^{2 +}$

he size of atoms increase due to the effect of extra shells of electrons being added. In a given period, the alkali metal is the largest size and halogen is the smallest.

cations among the options are $M g^{2 +}$ and $N a^{+}$ and the one with the higher charge is magnesium ion hence it will have the smaller size. The other two ions are negatively charged and as discussed above anions are greater in size from both the atoms and cations.

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Question: From NCERT NEET Derived PYQ

The basic theme of the periodic table is-

1. To classify the elements in a period according to their properties.

2. To classify the elements in a group according to their ionization enthalpy.

3. To classify the elements in periods and groups according to their properties.

4. To classify the elements in periods and groups according to their lustre.

Answer ▽

3. To classify the elements in periods and groups according to their properties.

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Question: From NCERT NEET Derived PYQ

Property used by Mendeleev to classify the elements was -

1. Brightness

2. Atomic weight or mass

3. Number of isotopes

4. Lustre

Answer ▽

2. Atomic weight or mass

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Evolution of Periodic Table ( 15+ Qs)[From NCERT]

NEET Questions>
Chemistry>
Classification of Elements and Periodicity in Properties>
Evolution of Periodic Table ( 12 Qs)

C) A straight line not passing through the origin

If atomic number of an element of He-family is Z then which of the following atomic number will highest EA?
(1) Z - 2
(2) Z - 1
(3) Z + 1
(4) Z + 2

With reference to the diagram given, the van der Waals radius is equal to:

$A - A$

$B - A$

$B - D$

$A - C$

Which one of the following is different from the others with respect to valency?
A.Potassium
B.Ammonium
C.Barium
D.Lithium

The combining capacity of an atom or molecule is measured by its valency. Elements belonging to the same group of the periodic table tend to have the same valency. It is related to the number of electrons present in the outer shell.

Optios-
The atomic number of Potassium is 19, with electronic configuration 2,8,8,1 .So, it needs to lose 1 electron in order to attain stability. Therefore, it has the valency of +1

Lithium has an atomic number of 3, having electronic configuration 2, 1. So, it needs to lose only one electron in order to achieve stable configuration. So, its valency will be 1.

Barium belongs to group II, and it has 2 electrons in its outermost shell, i.e., 6s shell. It can readily lose these 2 electrons in order to attain stability. So, barium has valency of 2.

Ammonium has the chemical formula of

${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$
${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ . Its valency is +1 most of the time, because it consists of one free electron on the central metal atom nitrogen.

So, the correct option is C.

Which of the following ions is the smallest in size?
A) $C l^{-}$
B) $N a^{+}$
C) $M g^{2 +}$
D) $S_{2}^{-}$

C) $M g^{2 +}$

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Evolution of Periodic Table ( 15+ Qs)[From NCERT]

NEET Questions>Chemistry>Classification of Elements and Periodicity in Properties> Evolution of Periodic Table ( 12 Qs)

If a graph is plotted with the atomic number on x-axis and the square root of the frequency of a spectral line of characteristic X-rays on the y-axis, then it will beA) A straight line passing through the originB) A parabolaC) A straight line not passing through the originD) A rectangular hyperbola

C) A straight line not passing through the origin

If atomic number of an element of He-family is Z then which of the following atomic number will highest EA?(1) Z - 2(2) Z - 1(3) Z + 1(4) Z + 2

With reference to the diagram given, the van der Waals radius is equal to:

A−A

B−A

B−D

A−C

Which one of the following is different from the others with respect to valency?A.PotassiumB.AmmoniumC.BariumD.Lithium

The combining capacity of an atom or molecule is measured by its valency. Elements belonging to the same group of the periodic table tend to have the same valency. It is related to the number of electrons present in the outer shell.

Optios-The atomic number of Potassium is 19, with electronic configuration 2,8,8,1 .So, it needs to lose 1 electron in order to attain stability. Therefore, it has the valency of +1

Lithium has an atomic number of 3, having electronic configuration 2, 1. So, it needs to lose only one electron in order to achieve stable configuration. So, its valency will be 1.

Barium belongs to group II, and it has 2 electrons in its outermost shell, i.e., 6s shell. It can readily lose these 2 electrons in order to attain stability. So, barium has valency of 2.

Ammonium has the chemical formula of

[NH4H4]+[NH4]+ . Its valency is +1 most of the time, because it consists of one free electron on the central metal atom nitrogen.

So, the correct option is C.

Which of the following ions is the smallest in size?A) Cl−B) Na+C) Mg2+D) S−2

C) Mg2+

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NEET Questions>
Chemistry>
Classification of Elements and Periodicity in Properties>
Evolution of Periodic Table ( 12 Qs)

If atomic number of an element of He-family is Z then which of the following atomic number will highest EA?
(1) Z - 2
(2) Z - 1
(3) Z + 1
(4) Z + 2

$A - A$

$B - A$

$B - D$

$A - C$

Which one of the following is different from the others with respect to valency?
A.Potassium
B.Ammonium
C.Barium
D.Lithium

Optios-
The atomic number of Potassium is 19, with electronic configuration 2,8,8,1 .So, it needs to lose 1 electron in order to attain stability. Therefore, it has the valency of +1

${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$
${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ ${[N H_{4}]}^{+}$ . Its valency is +1 most of the time, because it consists of one free electron on the central metal atom nitrogen.

Which of the following ions is the smallest in size?
A) $C l^{-}$
B) $N a^{+}$
C) $M g^{2 +}$
D) $S_{2}^{-}$

C) $M g^{2 +}$