Which statement is completely accurate?

Atoms of the same element always have different atomic weights.
Atoms of the same element can have different numbers of neutrons.
Atoms of the same element always have different numbers of neutrons.
Atoms of the same element can have neutrons but exist without protons. c

Like a key in a lock, the shape of the. must bind with the. of the recieving neuron

What are two different ways you could find the value of a? explain these methods.

With the simplified model of the eye, what corrective lens (specified by focal length as measured in air) would be needed to enable a person underwater to focus an infinitely distant object? (be careful-the focal length of a lens underwater is not the same as in air! assume that the corrective lens has a refractive index of 1.62 and that the lens is used in eyeglasses, not goggles, so there is water on both sides of the lens. assume that the eyeglasses are 1.90