Which of the following oxides is the most basic oxide?

Which of the following ions has a pseudo-noble gas electronic configuration?

The correct decreasing order for metallic character is:

Which of the following elements is considered as a metalloid?

Among the oxides $SiO_2, SO_2, Al_2O_3$ and $P_2O_3$,the correct order of acidic strength is

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