<span>Groups are vertical, numbered 1 through 18, and have similar properties, so answer D. Most of the properties of groups are defined by the outermost electron in the shells of the elements. Horizontal delineations in the Periodic Table are known as periods.</span>
OPTION C
<h2>POTENTIAL ENERGY </h2>
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Molar mass of 13c = 13 grams
number of moles = mass / molar mass
therefore,
number of moles = 7 / 13
To know the number of atoms in 7/13 moles, we simply multiply the number of moles by Avogadro's number as follows:
number of atoms = (7/13) x 6.022 x 10^23 = 3.2426 x 10^23 atoms