What is the use of two eyes?

What is the necessity of eye donation? Explain

What is the function of cones in the eye?

What is the range of vision for normal eye?

What is the distance between object and eye lens, when the telescope is on normal adjustment?

An alloy is made up of two metals- copper and zinc. What is the name of that alloy and what are its uses?

What is blind spot of eye?

The nature has provided two eyes(instead of one)to us.What is the importance of this nature's gift?