solve all three questions, solution need step by step

Problem 4: Pressure in atmosphere As many of you are aware, the density and pressure in the atmosphere is not uniform. Both decrease significantly as we move higher up. We want to determine an approximate expression for both quantities using simple hydrostatics. a) Start from the conservation of momentum equations and calculate the pressure distribution for a gas at a height z above the ground. There is zero flow and the density is non-uniform. Assume that we have an ideal gas with isothermal temperature. b) Under what conditions can one assume the constant density result p=p0gz ? c) Using your result from part (a), can you estimate by what percentage does the air density decrease if we go from sea level to the top of Mt. Everest ( 8.8km above sea level)? Would this calculated value underestimate or overestimate the true value of air density, where in reality the temperature decreases as we go further into the atmosphere