What is the cause of farsightedness? the cornea is irregular. the cornea is opaque. the eyeball is shortened. the eyeball is elongated.

The eyeball is shortened.

Explanation:

Farsightedness, popularly known as difficulty seeing closely, is a common refractive problem, where the image in the eye forms after the retina rather than exactly over the retina, which hinders the brain's ability to process the image correctly. In farsightedness there is no difficulty in seeing objects from afar, but when you get closer, it becomes very difficult to focus on them.

The eyeball works the same way as a dark box: light enters the pupil and forms the image on the retina. The shape of the eye and cornea is perfect for the image to form in the right place (the macula), and then the information is sent to the brain by the optic nerve.

When you have farsightedness, the eyeball is a little shortened or the flatter cornea, so the image ends up forming after the retina, ie the image the retina captures is not correct.

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explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.