Which of the following halides cannot be hydrolysed?

An element $(X)$ when burnt in oxygen forms a neutral oxide $(XO)$ and an acidic oxide $(XO_2)$. The element $(X)$ is:

$A$ certain element forms a solid oxide which when dissolved in water forms an acidic solution. The element is:

Which ions are present in aluminosilicates?

Which one of the following is a correct set?

In the following reaction,identify the nature of the product formed by the complete hydrolysis of the underlined atom at $R.T.$:
$\underline{Cr}O_2Cl_2 + 2H_2O \longrightarrow H_2CrO_4 + 2HCl$