What is formed when sulfur trioxide gas is absorbed in concentrated sulfuric 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.

Galvanisation is a method of protecting:

In which state does the element phosphorus exist at room temperature?

Food cans are coated with tin and not with zinc because:

What is the chemical formula of rust?