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.

(N/A) $(i)$ Alloys generally have higher electrical resistivity than their constituent pure metals. This property allows them to produce more heat when current passes through them. Additionally,they do not oxidize (burn) readily at high temperatures.
$(ii)$ Gold is a noble metal and is highly resistant to corrosion. It does not react with oxygen,moisture,or atmospheric gases,which is why it retains its luster for years.
$(iii)$ Iron reacts with oxygen and moisture present in the air to form hydrated iron$(III)$ oxide,commonly known as rust. Painting the grill creates a protective barrier that prevents the iron from coming into contact with air and moisture,thereby preventing rusting.