Important questions of periodic classification of elements

A.     MULTIPLE CHOICE QUESTIONS

1.    If two members of a Dobereiner triad are calcium and barium, then the third member of the triad is

    (a)Magnesium

    (b)Strontium

    (c)Caesium 

    (d)Sodium

        2.   An element which is an essential constituent of all organic compounds belong to:

            a .   Group 1

       b.   Group 14

        c.   Group 15

       d.  Group 16

       3.      Arrange the following elements in the order of their increasing non-metallic character–

               Li, O ,  C ,Be ,F

            a. F<O<C<Be <  Li

             b.    Li<Be<  C<O<F   

              c..   F<C<O<Be<Li

              d.  (iv)F<O<Be<C<Li 

        FILL IN THE BLANKS

       4.      Barium belongs to the same group as that of Magnesium so the formula of barium nitrate and magnesium sulphate is                                                     and                    .

       5.      Property used by Mendeleev to classify elements in his periodic table was .-------

       6.      The Modern Periodic Table consists of   periods  and     groups.

      ONE MARK QUESTIONS

       7.      Name the two elements that have two electrons in their outer most shells.

      8.      Name  the  element having  electronic  configuration 2,8,2.

       9.      The law of octaves was applicable up to which element.

        ASSERTIONS AND REASONS

      For the question numbers 10, 11 and 12, two statements are given- one labelled Assertion

     (A) and the other labelled Reason (R) . Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:     

(a) Both A and R are true and R is the correct explanation of A.

    (b) Both A and R are true but R is not the correct explanation of A.

     (c) A is true but R is false.

     (d) A is false but R is true.

       10.    Assertion: Li, Na, K form Doberiners triads

            Reason: Atomic mass of Na is roughly the average of the atomic mass of Li and K.

       11.    Assertion: Silicon is a metalloid.

            Reason: Silicon shows properties of only non- metals.

      12.   Assertion: Magnesium belongs to the 3rd period of the modern periodic table.

           Reason:   The valence electrons of magnesium are two. 

     THREE MARK QUESTIONS

       13.  (a)The atomic radius of hydrogen is 37pm. Express it in meters. 

             (b)How does atomic size vary in a group and a period?

              (c)If an element has an atomic number 18, mention the group to which it belongs.

       14. (a)An element has an electronic configuration 2, 8, 6. Explain its position in the periodic table.   

         (b)The size of the sodium atom is bigger than that of the hydrogen atom. Why?

          (c)Which has a greater atomic size-Cl or Br?