What is meant by the least distance of distinct vision?

$(a)$ How does the sky appear from the surface of the moon?
$(b)$ What is the cause of the blue colour of the ocean?

At noon,the sun appears white because:

$(i)$ Write the range of distance for a person having normal vision.
$(ii)$ $A$ person needs to use glasses for reading a newspaper. Identify the defect in his vision and the type of lens he would need to correct it.
$(iii)$ Sometimes when we enter into a dark room from bright sunlight,we are unable to see objects clearly. Why?

Which liquid fills the space behind the cornea?

Chickens can see only in bright light. What type of cells is present in their retina?