A. What is a period on the periodic table?

In chemical bonding: Arrangement of the elements. The horizontal rows of the periodic table are called periods. Each period corresponds to the successive occupation of the orbitals in a valence shell of the atom, with the long periods corresponding to the occupation of the orbitals of a d subshell.

Explanation:

the number of protons in the nucleus of a given element. has slight luster and conducts electricity at high temperatures like metal.but like a nonmetal,boron is brittle and does not conduct electricity well at low temperatures. in graphite, carbon is a soft,brittle solid.it is reflective,ductile,or malleable.

c. is the answer

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