At $150^oC$ the decomposition of acetaldehyde to methane is first order reaction. If rate constant for reaction at $750^oC$ is $0.05m^{-1}$, how long does it take a concentration of $0.04\;mol\;L^{-1}$ of acetaldehyde to reduce concentration of $0.03\;mol\;L^{-1}$?
