A student notes that a chunk of wood is much lighter after it has been burned. He concludes that burning a substance destroys some of the mass in that substance. Do you agree or disagree with this statement? Explain
your reasoning.

B- at night

In eyes of the humans, and many other animals there are two types of receptors, the rods, and the cones. The cones have an important role in color vision and they possess different types of pigment which enable color vision.
On the other hand, the rods are more sensitive to light, and they are responsible for black and white vision.
Therefore, an increase in the number of rods can enable the animal to see betther in the dark.