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<span>the rapid expansion of matter from a state of extremely high density and temperature that according to current cosmological theories marked the origin of the universe.</span>
Answer:
All the members of a group of elements have the same number of valence electrons and similar chemical properties.
Explanation:
The vertical columns on the periodic table are called groups or families because of their similar chemical behavior.
Clorine gas was formed at the <em><u>positive</u></em><em><u> </u></em><em><u>electrode</u></em><em><u>.</u></em><em><u> </u></em>