How would a descriptive model of Earth's layers be categorized? a. abstract model
b. prototype model
c. concrete model
d. conceptual model

Noble gases is far right

No. an alpha particle is a pair of protons and a pair of neutrons, i.e. a helium

Six base units were recommended: the metre, kilogram,second, ampere, degree kelvin (later renamed kelvin), and candela. in 1960, the 11th  cgpm  named the system the international system of units, abbreviated si from the french name, le système international  d'unités.

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