Answer:
Transition metals.
Explanation:
Transition metals are present at the middle of periodic table.
These metals have similar properties.
They have high melting and boiling points.
They all have high densities because of delocalization of d-electrons and metallic bonding.
Most of transition metal such as manganese, titanium and chromium are used to make the iron alloy because they are very good corrosion resistant material and also light weighted.
They are used to make lightweight steel.
Among transition metals osmium is more denser than others.
These have high strength and are very hard metals.
