$12140$ Consider a surface at $900$ K$.$ The spectral blackbody emissive power at a wavelength of $50$m is $($a$)3\mathrm{.}2$W$/$m$2$m$($b$)9\mathrm{.}6$W$/$m$2$m$($c$)24$W$/$m$2$m $($d$)76$W$/$m$2$m$($e$)108$W$/$m$2$m