Radium-223 id a radioactive isotope with a half-life of 11.4 days. approximately how long will it take for the activity of a sample 223ra to decease to 2.50% of its initial value

It will take 61 days for the activity of a sample Ra-223 to decease to 2.50% of its initial mass.

Explanation:

Initial mass of the Radium-223= x

Final mass of the Radium-223 left after time t = 2.50% of x= 0.025x

Time taken by the sample = t

Half life of the Radium-223 =

Formula used :

where,

= initial mass of isotope

N = mass of the parent isotope left after the time, (t)

= half life of the isotope

= rate constant

It will take 61 days for the activity of a sample Ra-223 to decease to 2.50% of its initial mass.

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.