Answer:
I am black when you buy me, red when you use me. When I turn white, you know it's time to throw me away. What am I?
I begin and have no end and I end all that begins. What am I?
I have hundreds of ears but cannot hear a thing. What am I?
I have numbers on my face but can't find 13 any place. What am I?
I build up castles. I tear down mountains. I make some men blind, I help others to see. What am I?
It flows out of the soil, It burns you if it boils, And holds us in its coils, More valuable than gold, As black as it is old.