A scientific law is a statement that is universally accepted and answers the "how?" question.
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Elements in group 1-2, 13-18, the number of valence electrons is related to the group number. For example, in the first group, the alkali metals there is one valence electron, however in group 13, there are 3 valence electrons. Valence electrons are also known as the outershell electrons.
Answer:
it is a viral disease . it is infected by one person to other .