Concave Mirror
Convex Mirror
Plane Mirror
Concave Lens
Mahatma Gandhi
Jawahar Lal Nehru
J. B. Kripalani
Sardar Vallabhbhai Patel
having septic tanks for each house
checking mixing of industrial waste with water bodies
use of degradable pesticides
all of the above
the upper flange
the web
the lower flange
Any of these
25 Hz
50 Hz
100 Hz
0.02 Hz