A yellow coloured elementary substance “X” when mixed with another element “Y” and the mixture is heated, a solid substance “Z” is formed, “Z” when treated with dilute sulphuric acid, a gas evolves with rotten egg smell. Element “Y” shows magnetic property. Identify X, Y, Z and also comment on the following:
i) Magnetic property of Z.
ii) Composition of Z.
iii) Type of change(s) taken place.