Answer:
Iris
Explanation:
The iris seems to be the illuminated portion of the eyes which really covers the pupil. It controls the amount of light reaching the eye. The lens is indeed a translucent layer of the retina that serves to concentrate light and objects on the lens.
Answer:
Hematite and magnetite
Explanation:
Minerals such as Iron don’t occur alone due to its interaction with other elements. The Iron’s major source is usually through ores such as Hematite, Magnetite, limonite etc.
However Pure magnetite contains 72.4 percent iron and pure hematite contains 69.9 percent. They have the highest percentage of iron thereby making them the main sources.
In scientific notation", that number would be written as
6.81 x 10⁻⁴ .