The reactivity of the following compounds toward water is in the order:

In $s-$block,on moving down the group,the reactivity of metals with water and air increases. Which of the following factors has no significance for this trend of reactivity?

The periodic table consists of $18$ groups. An isotope of copper,on bombardment with protons,undergoes a nuclear reaction yielding element $X$ as shown below. To which group,element $X$ belongs in the periodic table?
${}_{29}^{83}Cu + {}_{1}^{1}H \rightarrow 6{}_{0}^{1}n + {}_{2}^{4}\alpha + 2{}_{1}^{1}H + X$

Identify the amphoteric oxide from the following.

Which of the following is the correct order of acidic strength?

The order of reactivity of $K$,$Mg$,$Zn$,and $Au$ with water is