Question

An element R belongs to IVA(14) group and 3rd period in the periodic table. Arrange the elements that are placed below ‘R’ in the increasing order of atomic size.
(A) Ge > Sn > Pb
(B) As > Sb > Bi
(C) Ge < Sn < Pb
(D) As < Sb < Bi

Answer 1

Hint: The fourteenth group in the periodic table is Carbon family. As a general trend of periodic table, atomic size increases down the group.

Complete step by step answer: We know that, the fourteenth group of periodic table is Carbon family which consists of Carbon (C), Silicon (Si), Germanium (Ge), Tin (Sn) and Lead (Pb). So, the third period element in this group is Silicon (Si). Therefore, the element ‘R’ is Silicon (Si). From this, it is clear that the elements below the ‘R’ are Germanium (Ge), Tin (Sn) and Lead (Pb). According to the general trend of periodic properties, the atomic size increases down the group due to increase in the number of shells. There are four, five and six shells in Germanium, Tin and Lead respectively. So, Germanium has a small size as compared to Tin and Lead. Also, Lead has a large size as compared to Germanium and Tin. Therefore, the increasing order of atomic size is Ge < Sn < Pb. So, the correct option is (c).

Note: You need to know a good understanding of periodic tables and elements to solve this kind of question. Don’t be confused with the elements of the fourteenth group and fifteenth group. Also, take care of any anomalies present in this type of periodic properties problem.