The primary role of the carbonic-acid-bicarbonate buffer system is to

The primary role of the carbonic-acid-bicarbonate buffer system is to neutralize the hydronium ions forming carbonic acid and water when any acidic substance enter the bloodstream.

Explanation:

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the density of gold = 19.3 g/cm3

the relation between density and mass and volume is

density = mass / volume

given :

mass of gold = 13 g

density = 13g / volume = 19.3

volume = 13 /19.3 = 0.67 cm^3

thus volume of gold nugget = 0.67 cm^3

you gotta add the following molecules so we can give u an answer

explanation: