For the first order reaction, X→Y the time taken for 90% completion of the reaction is 666 minutes. Time taken for 93.75% completion of the reaction will be ------ minutes

t90%t50%=2.303K log 100100-902.303K log 100100-50; t90%t50%=1 log 2 t90%=3.33t50%; t50%=6663.33=200 minutes ; Conclusion :       t99.9%=10t50%;        t75%=2t50%;     t87.5%=3t50%;   t93.75%=4t50%; t 96.875%=5t50%;