After a time equal to four half lives, the amount of radioactive material remaining undecayed is-

After an interval of one day , 1//16th initial amount of a radioactive material remains in a sample. Then, its half-life is .

After an interval of one day , 1//16th initial amount of a radioactive material remains in a sample. Then, its half-life is .

After an interval on one day 1//6th of the initial amount of a radioactive material remains in a sample. Then its half life is

A sample contains 16 gm of radioactive material, the half-life of which is two days. After 32 days, the amount of radioactive material left in the sample is

A sample contains 16 gm of radioactive material, the half-life of which is two days. After 32 days, the amount of radioactive material left in the sample is

After two hours 1//6 th of the initial amount of a certain radioactive isotope remains undecayed. The half life of the isotope is :

After two hours, one sixteenth of the starting amount of a certain radioactive isotope remained undecayed. The half-life of the isotope is