CBSE Pathshala

Chapter wise test-Periodic Classification of elements 2 Marks Questions [2 x 5 = 10 ] 1. An element has electronic configuration 2, 8, 3. What is the atomic number of this element? To which (i) group and (ii) period this element belong? 2. State the positions of (i) isotopes of the same element and (ii) hydrogen in the Modern Periodic Table. 3. How does the tendency to gain electrons change as we go down the 16th group of periodic table? Why? 4. Give reasons for the following :  (a) Lithium atom is smaller than sodium atom. (b) Chlorine (atomic number 17) is more electronegative than sulphur (atomic number 16) 5. (a) State the Modern Periodic Law.  (b) Name the element which has twice as many electrons in its second shell as in its first shell. Write its electronic configuration also. 3 Marks Questions [ 3 x 5 = 15 ] 1. An element X belongs to group 17 and third period of the periodic table.  (a) Write electronic configuration of the element. What is it...

                                 Board Solved Questions Set-01 Q.1. Why does silicon is classified as Metalloid? Ans: Silicon is gray color solid at room temperature with very high melting point and boiling point that lose or gain 4 electrons  [  3s 2 , 3p 2 ] having both metallic and non metallic properties so it is classified as Metalloid eg. Sio 2 Q.2.Why inert gases have zero valencies? Ans: It is because Inert gases have 2 or 8 electrons in valence shell. Q.3. How is valency of an element determined? Ans: The valency of an element measures its ability to combine with other elements. The valency is determined by knowing place in periodic table.. All the elements in group VIII have eight electrons in their outer shells,...

Q.1. Why does silicon is classified as Metalloid? Ans: Silicon  is gray color solid at room temperature with very high melting point and boiling point that lose or gain 4 electrons [   3s 2 , 3p 2 ] having both metallic and non metallic properties so it is classified as Metalloid eg. Sio 2 Q.2.Why inert gases have zero valencies? Ans: It is because Inert gases have 2 or 8 electrons in valence shell. Q.3. How is valency of an element determined? Ans: The valency of an element measures its ability to combine with other elements. The valency is determined by knowing place in periodic table. . All the elements in group VIII have eight electrons in their outer shells, and thus have a valency of zero (highly stable). Elements in group I just have one valence electron in their outer shells and thus have a valency of one. Q.4. why could no fixed position be given to hyderogen in Mendleev’s Periodic table? Ans: Hydrogen placed in the first column above ...