The half-life of radium is 1600 years. After how many years 25 % of a radium block remains undecayed ?

The half-life of radium is 1600 years. After how many years 25% of radium block remains undecayed?

The half-life of radium is 1600 years. After how many years will one gram of the pure radium be reduced to one centigram?

The half life of radium is 1500 years. After how many years will one gram of pure radium (i) reduce to 1 centigram? (ii) lose one milligram?

Half-life of radium is 1,620 years. After how many years 0.75 mg of radium will be disintegrated out of its initial mass of 1 mg.

Half life of radium is 1600 years. Its average life:

The half-life of radium is 1500 years . In how many years will 1 g of pure radium be reduced to one centigram?

The half-life of radium is 1500 years . In how many years will 1 g of pure radium be reduced to one centigram?

The half-life of radium is 1500 years. After how many years will one gram of the pure radium (i) reduce to one centigram ? (ii) lose one milligram ?