The decay of 40k has a half of 1.3 × 109 years. the age of the earth is estimated at 4.6 × 109 years. the decay of 40k is a major heat source for the earth's interior. relative to today, how much more heat was produced by 40k in the early archaeon era or 3.9 × 109 years ago?

What is the overall order of reaction for rate = k[no]2[o2]

As changes in energy levels of electrons increase, the frequencies of atomic line spectra they emit

)benzene and toluene form nearly ideal solutions. consider an equimolar solution of benzene and toluene. at 20 °c the vapour pressures of pure benzene and toluene are 9.9 kpa and 2.9 kpa, respectively. the solution is boiled by reducing the external pressure below the vapour pressure. calculate (i) the pressure when boiling begins, (ii) the composition of each component in the vapour, and (iii) the vapour pressure when only a few drops of liquid remain. assume that the rate of vaporization is low enough for the temperature to remain constant at 20 °c.