Please help ! After 4.00 years, 2.000 g of a radioisotope remains from a sample that had an original mass of 4.00g. Calculate the half-life of this mystery radioisotope. How much of the radioisotope remains after 20.0 years? Show calcs and don't forget sig fig processes.

In vapor-liquid equilibrium in a binary mixture, both components are generally present in both phases. how many degrees of freedom are there for such a system? the reaction between nitrogen and hydrogen to form ammonia occurs in the gas phase. how many degrees of freedom are there for this system? steam and coal react at high temperatures to form hydrogen, carbon monoxide, carbon dioxide, and methane. the following reactions have been suggested as being involved in the chemical transformation: