Atom: Finally, there is the ever-so-tiny atom. It takes extremely powerful microscopes to view these units of matter (anything that has mass and takes up space). Elements such as carbon,
oxygen and hydrogen are composed of atoms. Atoms bonded together to make molecules. For
example, a water molecule consists of two hydrogen atoms bonded to an oxygen atom. Atoms
represent the smallest and most specific unit of this hierarchical structure.
What does this paragraph explain that other sections DO NOT?
(A)
that atoms are at the top of the pyramid of life
(B)
that molecules are made up of atoms
(C)
that atoms can only be seen with a microscope
(D)
that molecules and atoms are small units
Yes

Irrigation channels that require regular flow monitoring are often equipped with electromagnetic flowmeters in which the magnetic field is produced by horizontal coils embedded in the bottom of the channel. a particular coil has 100 turns and a diameter of 6.0 m. when it's time for a measurement, a 4.5 a current is turned on. the large diameter of the coil means that the field in the water flowing directly above the center of the coil is approximately equal to the field in the center of the coil. the field is directed downward and the water is flowing east. the water is flowing above the center of the coil at 1.5 m/s . what is the magnitude of the field at the center of the coil? what is the direction of the force on a positive ion in the water above the center of the coil? what is the magnitude of the force on an ion with a charge +e?