The metal that gives hydrogen gas upon treatment with both acid as well as base is

There are four identical containers,initially evacuated,and equal moles of the mentioned compounds are taken in each container (as shown in the diagram). The temperature is kept at $500 \ ^oC$ in each container,which are connected to a manometer. If the heights of the $Hg$ column recorded in the manometers are $x_1, x_2, x_3,$ and $x_4$ respectively,then the relation between $x_1, x_2, x_3,$ and $x_4$ is:

Select the correct statement.

Which of the anhydrous salts,when it comes in contact with water,turns blue?

Present a comparative account of the alkali and alkaline earth metals with respect to the following characteristics :
$(a)$ Tendency to form ionic/covalent compounds.
$(b)$ Nature of oxides and their solubility in water.
$(c)$ Formation of oxosalts.
$(d)$ Solubility of oxosalts.
$(e)$ Thermal stability of oxosalts.

What is the chemical formula for green vitriol?