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?

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.

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 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 ?