CBSE Class 10 Chemistry Periodic Classification Of Elements Worksheet Set B

Question : An element belongs to period 2 and group 2 the number of valence electrons in the atoms of this element is
(a) 2
(b) 4
(c) 3
(d) 1
Answer : A

Question : Electronic configuration of Al⁺³ is
(a) 2, 8, 3
(b) 2, 8, 8
(c) 2, 8
(d) 2, 8, 8, 3
Answer : C

Question : Which of the following sets does not belong to a group?
(a) Li, Na, K
(b) B, C, N
(c) B, Al, Ga
(d) O, S, Se
Answer : B

Question : Element belonging to which of the following atomic numbers 11, 19, 14, 18, 23 belong to the same period?
(a) 11, 14, 23
(b) 11, 18, 20
(c) 11, 14, 18
(d) 14, 19, 23
Answer : C

Question : Identify the group which is not a Döbereiner triad
(a) Li, Na, K
(b) Be, Mg, Cr
(c) Ca, Sr, Ba
(d) Cl, Br, I
Answer : B

Question : Which of the given elements A, B, C, D, and E with atomic number 3, 11, 15, 18, 19 respectively belong to the same group
(a) A, B, C
(b) B, C, D
(c) A, D, E
(d) A, B, E
Answer : B 

Question : Two elements X and Y have —
(i) X has 17 protons 18 neutrons
(ii) Y has 17 protons and 20 neutrons
Both X and Y are—
(a) Isobars
(b) Isotopes
(c) Isotones
(d) None of the above
Answer : B

Question : An element ‘X’ is placed in group 13 and third period of the Periodic Table. It burns in oxygen to form an oxide which is amphoteric in nature. Identify the chemical formula of its chloride
(a) CCl₄
(b) BCl₂
(c) GaCl₃
(d) AlCl₃
Answer : D 

Question : In the Modern Periodic Table calcium (Z = 20) is surrounded by the elements with atomic numbers 12, 19, 21, and 38 which of the following will have physical and chemical properties resembling calcium.
(a) 12, 20, 38
(b) 12, 19, 20, 38
(c) 19, 20, 38
(d) 12, 19, 20
Answer : A

Case Study Questions

Question : How electronegativity varies in a period?
(a) Increases down the group
(b) Decreasing down the group
(c) First increases then decreases down the group
(d) Vary independently
Answer : B

Question : Which element has highest electronegativity?
(a) C
(b) N
(c) O
(d) F
Answer : D

Question : What happens to tendency to gain electron in a period?
(a) Increases,
(b) Decreases,
(c) Remaining same,
(d) First increases then decreases.
Answer : A

Question : How electronegativity varies in a period?
(a) Increases from left to right
(b) Decreases from left to right
(c) First increases then decreases
(d) Vary independently
Answer : A

Question : Which of the following has least electronegativity?
(a) Li,
(b) Be,
(c) O,
(d) N
Answer : A

Question : Element X forms a chloride with the formula XCl₂, which is solid with a high melting point. X would most likely be in the same group of the Periodic Table as
(a) Na
(b) Mg
(c) Al
(d) Si.
Answer : As the formula of chloride of element X is XCl₂, it is a metal with valency 2 as it has a high melting point and is combining with Cl which is a non-metal having valency 1. Of the given elements, valency of (b) Mg is 2 (Atomic No. 12). Therefore, X will be in the same group as Mg in the Periodic Table. 

Question : How many groups and periods are there in the Modern periodic table?

Question : What was the prediction of Mendeleev regarding the gaps in his periodic table?

Question : How is valence of an element determined?

Question : What will be the valence of an element having atomic number 16?

Question : How does valence vary in going down a group?

Question : Why inert gases have zero valences?

Question : What would be the valence of an atom containing 8 electrons in its outermost shell?

Question : How does the electronegative character of elements vary along a period of the periodic table?

Question : The present classification of elements is based on which fundamental property of elements?

Question : Among first ten elements in the modern periodic table name the metals present.

Question : Metals are on which side of Modern periodic table?

Question : Name two elements, other than Gallium, whose existence was predicted by Mendeleev.

Question : State Modern Periodic law.

Question : Write the name given to the vertical columns in a periodic table.

Question : What name is given to the horizontal rows in a periodic table?

Question : Why does silicon is classified as Metalloid?

Question : Name the scientist who proposed modern periodic law? On which fundamental property of elements it is based?

Question : Why could no fixed position be given to hydrogen in Mendeleev’s Periodic table?

Question : What are metalloids? Give two examples.

Question : In group 1 of periodic table three elements X, Y and Z have atomic radii 133pm , 95pm and 65pm respectively giving a reason, arrange them in the increasing order their atomic number.

Question : How and why does the atomic size vary as you go down the group?

Question : Arrange the following is descending atomic size Na, Mg, K.

Question : Give the name and electronic configuration of second alkali metal? 

Question : What is the similarity in the electronic configuration of Mg, Ca and Sr? 

Question : Which is bigger in size Na OR K? 

Question : Name three elements which behave as metalloids? 

Question : Alkali metals form positive ions why?