Name the major fuel component of biogas. What are its other combustible components? Draw a simple labelled diagram of a fixed dome type biogas plant. What is the use of the residual slurry and why?

(N/A) The major fuel component of biogas is Methane $(CH_{4})$.
Other combustible components include Hydrogen $(H_{2})$,Hydrogen Sulphide $(H_{2}S)$,and Carbon Monoxide $(CO)$.
Diagram: (Refer to the provided image of the fixed dome type biogas plant).
The residual slurry (spent slurry) is used as manure because it is rich in nitrogen and phosphorus,which are essential nutrients for plant growth.