What are the various non-commercial sources of energy?
The solar energy, wind energy and tidal energy are the non-conventional energies. India being a tropical country, has almost unlimited potential for producing all three types of energy using cost effective technology. Cheaper electricity can be produced by solar, wind, tidal, firewood and cow dung. 
Differentiate the six systems of Indian medicine.
Explain the term 'infrastructure'.
Discuss the reforms which have been initiated recently to meet the energy crisis in India.
Explain the two categories into which infrastructure is divided. How are both interdependent?
