A radioactive element X with half life 2 h decays giving a stable element Y. After a time t, ratio of X and Y atoms is 1:16. Time t is?
A radioactive element X converts into another stable element Y. Half-life of X is 2 h. Initially only X is present. After time t, the ratio of atoms of X and Y is found to be 1 : 4, then t in hour is