Brass is an alloy of

In the $Bayer$ process,what is obtained when concentrated $NaOH$ is added to bauxite?

Which non-metal element exists in a liquid state at room temperature?

In the presence of which catalyst is vegetable ghee prepared from vegetable oil?

Which of the following oxide$(s)$ of iron would be obtained on prolonged reaction of iron with steam?

Give reasons for the following:
$(i)$ Alloys are used in electrical heating devices rather than pure metals.
$(ii)$ Gold ornaments look new even after several years of use.
$(iii)$ An iron grill should be painted frequently.