What is the correct order comparing the acid strengths of $HF$,$HCl$,$HBr$,and $HI$?

Which one of the following reactions does not occur?

The correct order of acidic strength is:

Identify the most acidic oxide among the following oxides based on their reaction.

Identify the group and valency of the element having atomic number $119$. Also,predict the outermost electronic configuration and write the general formula of its oxide.

With the help of the following reactions,arrange the metals $A$,$B$,$D$,and $E$ in decreasing order of their reactivity:
$(I)$ $B + ANO_3 \longrightarrow BNO_3 + A$
$(II)$ $A + HCl \longrightarrow ACl + \frac{1}{2} H_2$
$(III)$ $D + ECl \longrightarrow DCl + E$
$(IV)$ $D + HNO_3 \longrightarrow$ $H_2$ gas is not evolved