Question

Which pair of elements will react together most violently?
A. Chlorine and lithium
B. Chlorine and potassium
C. Iodine and lithium
D. Iodine and potassium

Answer 1

To answer this question the periodic properties of the elements from different groups should be known. A periodic table is a great source of information about the elements and their relation to each other. Changes of different periodic properties. The elements in periodic tables are arranged in a way that every element of each group show similar physical characteristics and chemical characteristics

Complete step by step answer:
Halogens are the most electronegative atoms of each period of the periodic table. Top to bottom of the halogen group size increases because of the number of electrons as well as the number of shells increases. Now with increasing the number of shells their atomic mass is also increased and electronegativity decreases. therefore, the reactivity of halogen decreases.
In the case of the periodic table from left to right metallic character decreases and non-metallic character increases as well as the electropositivity of the element decreases and electronegativity increases.
In the case of the extreme left of the periodic table, the metallic character is highest. In the case of metals top to bottom group size increases because of the number of electrons as well as the number of shells increases. Now with increasing the number of shells their atomic mass is also increased and electropositivity increases. Therefore, the reactivity of metals increases.
Now among the given options, the reaction between Chlorine and potassium will be most violent. This is because according to the periodic properties the reactivity of potassium and chlorine is very high.

So, the correct answer is, B.

Note: Due to the high atomic mass of the bottom elements of this group, the physical state of the bottom element of halogen is solid at room temperature. And due to low molecular mass top elements are in a gaseous state at room temperature. But bromine is in the middle of the group and also the molecular mass of from is not large to be solid as well as low to be gas. Due to this reason, the physical state of bromine is liquid at room temperature