SEBA Class 10 Science Important Chapter 5 Periodic Classification of Elements

SEBA Class 10 Science Important Chapter 5 Periodic Classification of Elements Solutions English Medium As Per SEBA New Syllabus to each chapter is provided in the list so that you can easily browse through different chapters SEBA Class 10 Science Additional Solutions in English and select need one. SEBA Class 10 General Science Additional Notes English Medium Download PDF. SEBA Important Solutions for Class 10 Science.

SEBA Class 10 Science Important Chapter 5 Periodic Classification of Elements

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Periodic Classification of Elements

Chapter: 5

IMPORTANT QUESTION ANSWER

Q.1. The elements X, Y and Z belong to groups 2, 14 and 16 respectively, of the periodic table. 

(a) Which two elements will form covalent bond? 

(b) Which two elements will form an ionic bond? 

Ans: Let us write down the above given data more clearly as follows: 

Group 2	Group 14	Group 16
X	Y	Z

(a) We know that a covalent bond is formed between two non metal elements. 

Now, out of elements X, Y and Z the element Y and element Z are non – metals. Thus, the elements Y and Z will form covalent bonds. 

( b ) An ionic bond is formed between a metal and a non- metal. Now, out of the above given elements, the elements X is a metal and elements Z in non – metal. Thus the elements X and Z will form an ionic bond. 

Q.2. The electronic configuration of an element X is: 

K	L	M
2	8	6

(i) What is the group number of element X in the periodic on table? 

(ii) What is the period number of element X in the periodic table? 

(iii) What is the number of valence electrons in an atom of X? 

(iv) What is the valency of X? 

(v) Is it a metal or a non – metal? 

Ans: (i) From the above given electronic configuration we find the element X has 6 valence electrons. So the group number of element X in the periodic table is 6 + 10 = 16

(ii) Element X has 3 electron shells in its atom, so the period number of X is 3. That is X belongs to 3rd period of the periodic table. 

(iii) Element X has 6 valence electrons. 

(iv) Element X has 6 valence electrons so it needs 2 more electrons to complete its octet and become stable. Thus the valency of element X is 2. 

(v) The elements of group 16 are non – metals. So, X is a non – metal. 

Q.3. (a) On which side of the periodic table will you find metals? 

(b) On which side of the periodic table will you find non metals? 

(c) What is the name of those elements which divide metals and non – metals in the periodic table? 

Ans: (a) Left side.

(b) Right side.

(c) Metalloids. 

Q.4. (a) Name three elements that have a single electron in their outermost shells. 

(b) Name two elements that have two electrons in their Shouter most shells. 

( c ) Name three elements with completely filled outermost shells. 

Ans: (a) Lithium, sodium, Potassium.

(b) Magnesium, Calcium.

(c) Helium, Neon, m Argon. 

Q.5. Nitrogen (atomic number 7) and phosphorus (atomic number 15) belong to group 15 of the periodic table . Write the electronic configuration of these two elements. Which of these will be more electronegative? Why? 

Ans: Electronic configuration of Nitrogen = 2, 5 

Electronic configuration of phosphorous = 2, 8, 5 

Nitrogen will be more electronegative because its atom has small size due to which the attraction of its nucleus for the incoming electron is more. 

Q.6. An elements X belongs to group 2 and another element Y belongs to group 15 of the periodic table: 

( a ) What is the number of valence electrons in X? 

( b ) What is the valency of X? 

( c ) What is the number of valence electrons for Y? 

( d ) What is the valency of Y? 

Ans: (a) 2 

(b) 2 

(c) 5 

(d) 3 

Q.7. (a) What is the usual number of valency electrons and valency of group 18 elements of the periodic table? 

(b) What happens to the number of valence electrons in the atoms of elements as we go down in a group of the periodic table? 

Ans: (a) The usual number of valence electrons is 8 and valency is 0 (zero). 

(b) The number of valence electrons remains the same as we go down in group of the periodic table.

Q.8. The atomic numbers of the three elements X, Y and Z are 2, 6 and 10 respectively. 

(i) Which two elements belong to the same group? 

(ii) Which two elements belong to the same period? 

Ans: (i) X and Z 

(ii) Y and Z