Answer: the order of increasing atomic size is: Si < Sn < Pb
Step-by-step explanation:
The question requires us to arrange the elements Si, Pb and Sn in order of increasing atomic size.
The atomic size of different elements can be compared based on the atomic radius of the atoms. Considering the periodic table, the atomic radius tends to increase from right to left and from the top to the bottom of the table. Therefore, if we locate the elements Si, Pb and Sn on the periodic table, we can compare their size based on the atomic radius tendency.
Looking at a periodic table, we can locate the elements Si, Pb and Sn as it follows (highlighted in red):
Note that these elements belong to the same group and that Si is above Sn, that is above Pb.
Therefore, knowing that the atomic radius increase from the top (Si) to the bottom (Pb), the order of increasing atomic size is: Si < Sn < Pb