26. your mother will soon undergo some medical testing that will require her to swallow a radioactive

isotope as a tracer. she is nervous about having a radioactive substance in her body even though the

radiologist told her not to worry, as the isotope has a half-life of only 7 minutes. explain to her what

a half-life is, and the significance of the half-life being 7 minutes.

Most radioactive materials decay and they mostly have a decay rate. The time it takes for half of a radioactive material to decay is called half life.

The 7 minute significance of half-life simply points to the total time it takes after which half of the radioactive material would have completely decayed,

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-