2.34 a. An incident beam of 2.0-MeV gammas has an intensity of 1,200 photons/s cm2. What is its intensity after it passes through 8.0 cm of 40% porosity steel wool? Solid steel with a density of 7.85 g/cm3 has a mass absorption coefficient of 0.044 cm2/g for 2.0-MeV gammas. (Hint: air contribution is negligible.) b. If the steel wool is saturated with water whose mass ab- sorption coefficient is 0.049 cm2/g, what is the linear and mass absorption coefficient of the mixture? c. To what value will the water-saturated steel wool reduce the incident beam of 1,200 photon/s cm2 after it passes through 8.0 cm of it? 2.35 Calculate the number of hydrogen atoms per cubic centimeter for the following matters: (a) fresh water, (b) oil (C,H2, 0.8 g/cm), and (c) methane (CH4, 0.01 g/cm3).