Which property of argon makes it useful for potassium-argon dating? a. it decays into potassium. b. it is an unstable element. c. it remains trapped in rock. d. it is useful only for dating newer rock.

Potassium-argon dating:-

Potassium-argon dating method is used for dating of very old archaeological rocks. Geologist are using this method of dating for rocks as old as 4 billion years old. This method is based on calculation of the product of the radioactive decay of an isotope of potassium (K) into argon (Ar). Argon which is a noble gas, is a minor component of rock sample of geographical inyterest . When K decays to A r, it tremain trapped within the lattice as it is larger than the sapces between the other atoms in a crystal .

So the answer is C. It remains trapped in rock, this property of argon that is Ar make it useful for dating.

C

Explanation:

  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-

a) the particles of the chair are strongly held together.