List of top Physics Questions on Decay Rate asked in MHT CET

A radioactive element having half-life (30 min) is undergoing beta decay. The fraction of radioactive element remains undecayed after (90 min) will be

A radioactive element having half-life (30 min) is undergoing beta decay. The fraction of radioactive element remains undecayed after (90 min) will be

A radioactive element having half-life (30 min) is undergoing beta decay. The fraction of radioactive element remains undecayed after (90 min) will be

Radioactive materials A and B have decay constants ' \( 9\lambda \) ' and ' \( \lambda \) ' respectively. Initially they have same number of nuclei. The ratio of number of nuclei of material ' \( A \) ' to that of ' \( B \) ' will be \( \left( \frac{1}{e} \right) \) after time ' \( t \) '. So ' \( t \) ' is equal to

Half life of radio-active element is $1600$ years. The fraction of sample remains undecayed after $6400$ years will be