In which of the following compounds does hydrolysis take place through $S_N^1$ and $S_N^2$ mechanisms respectively?

Which of the following produces $NO_2$ gas on heating?

What is the product formed when ammonia reacts with excess chlorine?

Select the correct statement.

Nitrogen exists as $N_2$,whereas phosphorus exists as $P_4$. This is because ..........

Given below are two statements :
Statement $-I :$ The pentavalent oxide of group $-15$ element,$E_2O_5$,is less acidic than trivalent oxide,$E_2O_3$,of the same element.
Statement $-II :$ The acidic character of trivalent oxide of group $15$ elements,$E_2O_3$,decreases down the group.
In light of the above statements,choose the most appropriate answer from the options given below.