Neon has 2 isotopes. neon-20 has a mass of 19: 992 amu and
neon-22 has a mass of 21 amu. in any sample of 100 neon
atoms, 90 will be neon-20 and 10 will be neon-22. calculate
the average atomic mass.

Sylvanite is a mineral that contains 28.0% gold by mass. how much sylvanite would you need to dig up to obtain 77.0 g of gold? explain how you got your answer and the steps you took. you

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation:

Amixture initially contains a, b, and c in the following concentrations: [a] = 0.300 m , [b] = 1.05 m , and [c] = 0.550 m . the following reaction occurs and equilibrium is established: a+2b⇌c at equilibrium, [a] = 0.140 m and [c] = 0.710 m . calculate the value of the equilibrium constant, kc.