Standards for firewalls may be based on their thermal response to a prescribed radiant heat flux. consider a 0.25-m-thick concrete wall ( 2300 kg/m^3, 880 j/kg·k, 1.4 w/m·k), which is at an initial temperature of 25°c and irradiated at one surface by lamps that provide a uniform heat flux of 0.75·104 w/m^2. the absorptivity of the surface to the irradiation is 1.0. if building code requirements dictate that the temperatures of the irradiated and back surfaces must not exceed 325°c and 25°c, respectively, after 30 min of heating, will the requirements be met?