Question

1. the least reactive metal is found in

a) group 1
b) group 2
c) group 18
d) d - block

1. the most reactive non - metal is:

a) f
b) cl
c) o
d) s

1. which of the following ions is the smallest?

a) o²⁻
b) f⁻

Explanation:

Question 16

Group 1 (alkali metals) and Group 2 (alkaline earth metals) are highly reactive metals. Group 18 elements are noble gases, most of which are non - reactive. However, some d - block metals (transition metals) are less reactive. Among the options, the least reactive metals are in the d - block (e.g., gold, platinum). Group 18 has very few metals (only some under special conditions), and Group 1 and 2 are very reactive. So the least reactive metal is found in the d - block.

Among non - metals, reactivity generally increases as we move up a group and to the right in a period (except noble gases). Fluorine (F) is in Group 17, Period 2. Chlorine (Cl) is below F in Group 17. Oxygen (O) and Sulfur (S) are in Group 16. Fluorine has a high electronegativity and a small atomic size, which makes it very reactive. It is the most reactive non - metal.

For isoelectronic species (species with the same number of electrons), the ionic radius decreases with an increase in nuclear charge. \(O^{2 -}\) and \(F^-\) are isoelectronic (both have 10 electrons). The nuclear charge of O is +8 and of F is +9. Since F has a higher nuclear charge, it pulls the electrons more tightly, so \(F^-\) has a smaller ionic radius than \(O^{2 -}\).

Answer:

d) d - block

Question 17