The human eye forms the image of an object at its

Why is the blind spot so called?

What are the two colors of light called whose mixture produces white light?

Which of the following relationships regarding the wavelengths $\lambda$ of different colors of light is correct?

The colour of which part of the eye determines the colour of the eye of a person?

$A$ person is able to see objects clearly only when these are lying at distances between $50\, cm$ and $300\, cm$ from his eye.
$(a)$ What kind of defect of vision is he suffering from?
$(b)$ What kind of lenses will be required to increase his range of vision from $25\, cm$ to infinity? Explain.