Atoms and Nucle...

Half-life is measured by

The decay constant of a radioactive element is 1.5 × 10^–9 per second. Its mean life in seconds will be

Nucleus produced due to α–decay of the nucleus _ZX^A is

Which of the following processes represent a gamma-decay

The half-life of ²¹⁵At is 100µs. The time taken for the radioactivity of a sample of ²¹⁵At to decay to 1/16^th of its initial value is

A radioactive substance has an average life of 5 hours. In a time of 5 hours

A radioactive sample at any instant has its disintegrations rate 5000 disintegrations per minute. After 5 minutes, the rate 1250 disintegrations per minute. Then, the decay constant (per minute) is

A count rate meter shows a count of 240 per minute from a given radioactive source. One hour later the meter shows a count rate of 30 per minute. The half-life of the source is

Activity of radioactive element decreased to one third of original activity R₀ in 9 years. After further 9 years, its activity will be

A nucleus decays by β⁺ emission followed by a gamma emission. If the atomic and mass numbers of parent nucleus are Z and A respectively, the corresponding numbers for the daughter nucleus are respectively