Three elements A, B and C have 3, 4 and 2 electrons respectively in their outermost shell. Give the group number to which they belong in the Modern Periodic Table. Also, give their valencies.
Three elements A, B and C have 3, 4 and 2 electrons respectively in their outermost shell. Give the group number to which they belong in the Modern Periodic Table. Also, give their valencies.

Solution: A belongs to Group 13, B belongs to Group 14, and C belongs to Group 2. A belongs to Group 13 and B belongs to Group 14. The values of A, B, and C are 3, 4, and 2, respectively.