Which of the following oxides is the most acidic?

Of the following pairs,the one containing an example of metalloid elements in the periodic table is:

Which of the following is the most acidic?

In a periodic table, how does the basic character of oxides vary?

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

In the periodic table,metallic character of the elements shows which one of the following trends?