How does $SO_2$ gas behave when it is moist?

Elements of Group $16$ generally show lower value of first ionisation enthalpy compared to the corresponding periods of Group $15$. Why?

Assertion: $Ozone$ is a powerful oxidising agent in comparison to $O_2$.
Reason: $Ozone$ is diamagnetic but $O_2$ is paramagnetic.

Consider the following sulphur-based oxoacids: $H_2SO_3$,$H_2SO_4$,$H_2S_2O_8$,and $H_2S_2O_7$. Among these oxoacids,the number of those with a peroxo $(O-O)$ bond is $..........$

When a small amount of $KMnO_4$ is added to concentrated $H_2SO_4$,a green oily compound is obtained which is highly explosive in nature. The compound is:

Identify the element having general electronic configuration $ns^2 np^4$ from the following.