Initially P→4N0 Q→N0 Half life Tp→1 min TQ→2min Let after time t number of nuclei of P and Q are equalie, 2t/14N0=2t/2N0 4222tt=2t/2=2t/2=2=4 min Disactive nucleus or Nuclei of R =(4N0−244N0)+(N0−22N0)=4N0−4N0+N0−4N0=5N0−2N0=29N0