Question

what trend does the reactivity of most nonmetals show in a periodic table, excluding the noble gases?
random changes without any trends on the periodic table
changes according to trends on the periodic table
increases from left to right across the periodic table
decreases from left to right across the periodic table

Explanation:

Non - metals (excluding noble gases) have a trend in reactivity. As we move from left to right across a period in the periodic table, the reactivity of non - metals generally decreases. This is because as we move across a period, the atomic size decreases (due to an increase in nuclear charge which pulls the electrons closer to the nucleus), and the non - metals have a stronger hold on their valence electrons. For example, in period 2, fluorine (on the left among non - metals in period 2, excluding noble gas neon) is more reactive than oxygen, which is more reactive than nitrogen.

Answer:

decreases from left to right across the periodic table