Which of the following metals is the lightest?

Which of the following is a mineral of sulfur?

During the electrolytic refining of zinc,it gets :

Which alloy is used for making aircraft parts?

State reasons for the following:
$(i)$ Metals are good conductors of heat.
$(ii)$ Addition of some silver to pure gold for making ornaments.
$(iii)$ Inability of non-metals to displace hydrogen from dilute sulphuric acid.

$(a)$ List two differences between calcination and roasting in tabular form.
$(b)$ Which method will you use to reduce the following? Explain by giving a suitable example.
$(i)$ Oxides of less reactive metals.
$(ii)$ Oxides of moderately reactive metals.
$(iii)$ Oxides of highly reactive metals.