Telangana SCERT Class 10 Physical Science Chapter 7 Classification of Elements – The Periodic Table Solution

Telangana SCERT Class 10 Physical Science Chapter 7 Solution – Classification of Elements – The Periodic Table. Here in this post we provides Class 10 Physical Science Classification of Elements – The Periodic Table Telangana State Board Solution.  Telangana State Board English Class X Medium Students can download this Solution to Solve out Improve Your Learning Questions and Answers.

Telangana State Board Class 10 Physical Science Chapter 7 Classification of Elements – The Periodic Table Solution:



(Classification of Elements- The Periodic Table)


Exercise: –

1) What are the limitations of Mendeleeff’s periodic table?How could the modern periodic table overcome the limitations of Mendeleeff’s table?

Ans: – According to Mendeleev’s the physical and chemical properties of any element according to their atomic mass which seen as a limitation in the law. The modern periodic table uses atomic no of the element to find its characteristics for the measurements of different properties so we use this to overcome this situation.


2) Define the modern periodic Law. Discuss the construction of the long form of the periodic table.

Ans: – Modern periodic table states that the physical and chemical properties of the element will be according to their atomic number or electronic configuration. Whereas the previous concept was to keep the elements in periodic table was according to their atomic masses.

The long form of the modern periodic table has 18 vertical line is called group where as the 7 horizontal lines called period.


3) Explain how the elements are classified into s, p, d and f- block elements in the periodic tableand give the advantages of this kind of classification.

Ans: – The element which are classified into s, p, d, f- block are based on their electronic configuration. In chronological order the electron enter into s then p and then d and at last f block. While differentiating the classification we came to the certain places where we easily separate the similar property showing element in the same group and different properties of element to the other groups.


4)Write down the characteristics of the element having atomic number 17.

Ans: – • The electronic configuration of the element number 17 or chlorine is 1s^22s^22p^63s^23p^5.

  • The no of period in of the element atomic number 17 is 7.
  • The group no of chlorine is3.
  • Atomic no 17 is p block element.
  • The valance electron or no of electron in last two orbital of atomic number 17 is 7.
  • Atomic number 17 or chlorine is a non-metal.


5) Complete the following table using the periodic table. (AS1)

Ans: –

Period number Filling up orbital’s

(sub shells)

Maximum number of electrons, filled in all the sub shells Total no. of elements in the period
1 1s 2 2
2 2s,2p 8 8
3 3s,3p 18 8
4 4s,3d,4p 18 18
5 5s,4d,5p 18 18
6 6s(4f),5d,6p 32 32
7 7s,5f,6d,7p 32 Incomplete


6) Complete the following table using the periodic table.

Ans: –

Period number Total number of elements Elements

Total number of elements in

From To s p d f
1 2 H He 1 1 0 0
2 8 Li Ne 2 6 0 0
3 8 Na Ar 2 6 0 0
4 18 k kr 2 10 6 0
5 18 Ru Xe 2 10 6 0
6 32 Cs Rd 2 9 6 15
7 32 Fr Uuo 2 9 6 15


Application of concepts

1.) Given below is the electronic configuration of elements A, B, C, D.

A.1s2 2s2                      1. Which are the elements coming within the same Period.

B. 1s2 2s2 2p6 3s2        2. Which are the ones coming within the same group?

C. 1s2 2s2 2p6 3s2 3p3 .   3. Which are the noble gas elements?

D. 1s2 2s2 2p6.               4. To which group and period does the element ‘C ‘belong.

Ans: –  (1) A and the B elements belongs to the same period.

(2) B and C are in the same group.

(3) D is the noble gas elements or inert gas.

(4) From the upper electronic configuration,we assure that c belongs to 3rd period and 5th group.


4) a.) State the number of valence electrons, the group number and the period number of each element given in the following table:

Ans: –

Elements Valance electron Group number

Period number

Sulphur 6 6 3
Oxygen 6 6 2
Magnesium 2 2 3
Hydrogen 1 1 1
Fluorine 7 7 2
Aluminium 3 3 3


b.) State whether the following elements belong to a Group (G), Period (P) or Neither Group nor Period indicating the letters G or P or N.

Ans: –

Elements Group number

Period number

Li, C, O 2,2,2 1,4,6
Mg, Ca, Ba 2,4,6 2,2,2,
Br, Cl, F 4,3,2 7,7,7
C,S,Br 2,3,4 4,6,7
Al, Ci, Cl 3,3,3 3,4,7
Li, Na, K 2,3,4 1,1,1
C, N, O 2,2,2 1,1,1,
K, Ca, Br 4,4,4 1,2,7


5) Identify the element that has the larger atomic radius in each pair of the following and markit with a symbol (). (AS1)

(i) Mg , Ca (ii) Li , Cs (iii) N , P (iv) B , Al.

Ans: –

(i) Ca radius more than Mg;

(ii) Cs radiusmore as compare to Li.

(iii) Here p has radius more to nitrogen.

(iv) Al radius more as compared to B.


6) Identify the element that has the lower Ionization energy in each pair of the following and mark it with a symbol ().

(i) Mg , Na (ii) Li , O (iii) Br , F (iv) K , Br.

Ans: – (i) Na has low IE as compared to Mg;

(ii) Li has low ionization energy as compared to oxygen.

(iii) F has less ionization energy from Br.;

(iv) Ionization energy is more in potassium.


7) How does metallic property change when we move

 i.) Down in a group ii.) Across a period?

Ans: – (i) From up to down a group metallic character increase as the new shell adder and tendency of losing tendency of electron increases.

(ii) Across a period has always a tendency toloses the electron and this phenomenon decrease as nuclear charge increases so metallic character decrease.


8) On the basis of atomic numbers predict to which block the elements with atomic number 9,37, 46 and 64 belongs to?

Ans: – Comparing the electronic configuration of the atomic no we can tell the period of this element. Atomic no 9 has 7 valance electrons so we can say the period is 7 and s block element, atomic no 37 has 1 valance electron then period is 1 and p block element, atomic no 46 has 10 valance electrons so its period is 10, a d block element and the last element has atomic no 64 is f block element.


9) Using the periodic table, predict the formula of compound formed between an element X of group 13 another element Y of group 16.

Ans: –  By comparing the group number we can say that the formula is X2Y5.


Higher Order Thinking Questions

1) How does the positions of elements in the periodic table help you to predict its chemical properties? Explain with an example. (AS7)

Ans: – From the electronic configuration of an atom we can easily say about the position of that atom. If the valency of an atom is known to us then we can talk about its position in period as well its other characteristics.  Besides this the subshell no always helps us to tell its group no.

2)  In period 2, element X is to the right of element Y. Then, find which of the elements have these properties:

i) Low nuclear charge (ii) Low atomic size (iii) High ionization energy(iv)High electro negativity (v) More metallic character.

Ans: – (i) y has lower nuclear charge as compared to others.

(ii) From the element x has law atomic size.

(iii) x has ionization energy high from the others.

(iv) x is most electro negative in nature.

(V) y is more metallic in nature from the other elements.



1.)  Number of elements present in period – 2 of the long form of periodic table

a) 2 b) 8 c) 18 d) 32.

Ans: – option (b) 8.


2) Nitrogen (Z = 7) is the element of group VA of the periodic table. Which of the following is theatomic number of the next element in the same group?

a) 9 b) 14 c) 15 d) 17.

Ans: – Option (c) 15.


3.) Electron configuration of an atom is 2, 8, 7. To which of the following elements would it be chemically similar?

a) nitrogen(Z=7) b) fluorine(Z=9) c) phosphorous(Z=15) d) argon(Z=18).

Ans: – Option (b) fluorine.


4.) Which of the following is the most active metal?

a) lithium b) sodium c) potassium d) rubidium.

Ans: – Option (d) rubidium.

More Question and Answer (Extra)

Q.1) MCQ.

1.) Which of the following scientist defined an element

a) Robert Boyle

b) Doeringer

c) Newland

d) Mendeleev

2.) Who discovered law of octaves.

a) Newland

b) Doeringer

c) Robert Boyle

d) Mendeleev

3.) How many groups present in Mendeleev’s periodic table

a) 7

b) 8

c) 4

d) 6

4.) Who is the founder of modern periodic table

a) Newland

b) Mendeleev

c) Moseley

d) Robert Boyle

5.) How Many groups present in modern periodic table

a) 18

b) 16

c) 17

d) 7

6.) Which of the following is s block element

a) Al

b) P

c) O

d) Na

7.) 1 pm = _____ m

a) 10^-12

b) 10^-11

c) 10^-10

d) 10^11

8.) Ionization energy expressed in terms of_______

a) Kilo joule

b) Kilo joule per mole

c) joule

d) None of the above

2) Very short answers

1.) How does ionization energy changes across the group?

→Ionization energy decreases down the group.

2.) What is the relation of valency in a group

→The valency in a group remains same for all the elements

3.) Define electronegativity

→The electronegativity is defined as tendency of its atom to attract electron towards itself when it is bonded to another atom.

4.) What is screening effect?

→As the number of shells between nucleus and valence shell increases it can reduce the potential of nuclear charge on valence shell electrons and the shells between acts as a screen and lower the effect of nuclear charge this effect is called as screening effect.

5.) What is ionization energy?

→The energy required to remove an electron from outermost orbit or a shell of neutral gaseous atom this energy is called as ionization energy.

6.) What is atomic radius?

→The atomic radius is defined as the distance between nucleus and the

shell of the atom.

7.) How many electrons present in second group

→ Six

8.) How does electronegativity changes in a period?

→The electronegativity increases from left to right in a period

Q.3) short answer questions

1.) Explain the Dobereiner law of triads?

→ Dobereiner stated that when three elements with similar properties arranged in an ascending order of their atomic weights then atomic weight of middle element is an average of atomic weight of first and third element this statement is the Dobereiner law of triads

2.) Explain the limitations of law of triads

Limitations of law of triads

→ 1) All the known elements at that time could not be arranged in the form Of trials.

2) This law failed for very low mass or very high mass element.

3) As the techniques improved for atomic masses accurately, the law was unable to remain strictly valid.

3.) State the Newlands law of octaves.

→When elements are arranged in a ascending order of their atomic weights they fall into a pattern in which there properties repeat at regular intervals. Every at element from the given element has properties similar to that of the given element. Elements with similar chemical properties are to be present along a horizontal row.

4.) Write limitations of Mendeleev’s periodic table.

Limitations of Mendeleev’s periodic table

i) Anomalous pair of elements- certain elements of higher atomic weights precede those with lower atomic weight.

ii) Dissimilar elements placed together- elements with disable properties are placed in a same group as sub group A or sub group B. Cl is of 7A group and Mn is of 7B group but Cl is a nonmetal and Mn is metal.

Q.4) Long answer questions

1.) Describe modern periodic table in short

→The modern periodic table States the periodic law. The periodic law states that the properties of the elements are periodic function of their atomic numbers.  The vertical columns in the periodic table are known as groups. There are 18 groups in the periodic table. The horizontal rows in the periodic table are called as periods. There are 7 periods in the periodic table.  four blocks are present in the periodic table that are s block, p block, d block, f block. Periods are represented by Arabic numbers 1 to 7.  The number of main shells of the atom of a particular element decides in which period it belongs. For example, hydrogen and helium contain only one main shell K, so they are present in first period and so on.

2.) Write a note on metallic and non-metallic properties in a modern periodic table?

→ Metals generally show less electronegative character. In compounds they generally show attendance to remain as positive ions. This property of metals is called as electropositive property so the metals are electropositive elements

While nonmetals generally show more electronegative character due to their small radius. As we know sodium and magnesium are metals, aluminum and silicon are semi metals, Phosphorus Sulphur and chlorine are nonmetals hence metals are present on left hand side of the periodic table nonmetals are present on right hand side of the periodic table therefore metallic character decreases from left to right and nonmetallic character increases from left to right.

Updated: December 26, 2022 — 10:26 pm

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