For the electron configuration 1s2 the 1 represents?

What does the mass of 0.7891 mol of ferric oxide (fe2o3)

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.

Nuclear decay is the spontaneous decay of one element into a. an x-ray b. a ray of light c. another element