As a diffusion expert you are to calculate the thickness of Ag required to maintain at least a 99% Ag alloy on the surface of Cu for 5 years. The most accurate data you can locate is a study of D for Ag in Cu between 750 and 1050°C. Extrapolating these data to 150°C, you find that a 1 micrometer layer of Ag will last for 150 years. A laboratory test shows that a 1 micrometer silver layer completely dissolves in a sample over a weekend at 150°C. Why might the calculation of the rate at 150°C be invalid?

chemical digestion occurs in the stomach were hcl and pepsin forms chyme, the mouth in which salivary amylase breaks down starch to form bolus, and the small intestine specifically the duodenum.

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

hey there!

mass = 6.75 g

volume =   9 cm³

therefore:

d = mass / volume

d   = 6.75 / 9

d = 0.7 g/cm³

answer b