This table shows how the levels of classification have changed with each major scientist.

Which number belongs in the space labeled X?

5
7
8
10

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.

you didnt put any of the following

im doing test rn im going with 2 but ill give answer if itss wrong,   : )