Question

6. Write two elements for each of the following:
(i) Alkali metals,
(ii) Noble gases.

7. Account for the following:
(a) Cations are smaller in size than the corresponding atom.
(b) The noble gases were discovered very late.

8. The electronic configuration of four elements A, B, C and D is given as follows:
A - 2, 8
B- 2, 8, 1
C - 2, 8, 2
D- 2, 8, 8
(a) Which of them belong to the same period? Name the period.
(b) Which of them belong to the same group? Name the
group.

9. In Mendeléev's Periodic Table the elements were arranged in the increasing order of their atomic
masses. However, cobalt with atomic mass of 58.93 amu was placed before nickel having an atomic mass of 58.71 amu. Give reason for the same.

10.Write two points of differences between Mendeléev's Periodic Table and the Modern Periodic
Table.

11."Hydrogen occupies a unique position in Modern Periodic Table.” Justify the statement.​

Answer 1

Explanation:

Alkali metals=Na,k,Rb,Cs

Noble metals= Ar,kr,xe,Rn