Three elements A, B and C have atomic numbers 7, 8 and 9 respectively.
(a) What would be their positions in the modern periodic table ? (Mention group and period both)
(b) Arrange A, B and C in decreasing order of their size.
(c) Which one of the three elements is most reactive and why ?

Three elements 'X', 'Y' and 'Z' have atomic numbers 7, 8 and 9 respectively. (a) State their positions (Group number and period number both) in the Modern Periodic Table. (b) Arrange these elements in the decreasing order of their atomic radii. (c) Write the formula of the compound formed when 'X' combines with 'Z'.

Two elements 'A' and 'B' have atomic numbers 11 and 19 respectively. State their position in the Modern Periodic Table. Which element has bigger atomic radius. What is the nature of their oxides.

Three elements 'X', 'Y' and 'Z' have atomic numbers 7, 8 and 9 respectively. (i) State their positions (Group number and period number both) in the Modern Periodic Table. (ii) Arrange these elements in the decreasing order of their atomic radii. (iii) Write the formula of the compound formed when 'X' combines with 'Z'.

Five elements A,B,C,D and E have atomic numbers of 2,3,7,10 and 18 respectively. The elements which belong to the same period of the periodic table are:

Atomic number of three elements A. B and C are 10, 13 and 17 respectively:- Find their positions in the periodic table