Name two metals which will displace hydrogen from dilute acids,and two metals which will not.

Samples of four metals $A$,$B$,$C$ and $D$ were taken and added to the following solutions one by one. The results obtained have been tabulated as follows.

Metal	Iron $(II)$ sulphate	Copper $(II)$ sulphate	Zinc sulphate	Silver nitrate
$A$	No reaction	Displacement	No reaction	Displacement
$B$	Displacement	Displacement	No reaction	Displacement
$C$	No reaction	No reaction	No reaction	Displacement
$D$	No reaction	No reaction	No reaction	No reaction

Use the table above to answer the following questions about metals $A$,$B$,$C$ and $D$:
$(i)$ Which is the most reactive metal?
$(ii)$ What would you observe if $B$ is added to a solution of Copper $(II)$ sulphate?
$(iii)$ Arrange the metals $A$,$B$,$C$ and $D$ in the order of decreasing reactivity.

An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be

Define the following terms:
$(i)$ Mineral
$(ii)$ Ore
$(iii)$ Gangue

Give reasons: Aluminium is a highly reactive metal,yet it is used to make utensils for cooking.

Why do ionic compounds have high melting points?