43. We have a radioactive isotope called RI which has a half-life of 12 million years. A geologist
has used radiometric dating and determined the rock to be approximately 36 million years old
How many half lives have taken place?
(1 point)

Thus 3 half lives have taken place.

Explanation:

Expression for rate law for first order kinetics is given by:

where,

k = rate constant

t = age of sample

a = let initial amount of the reactant

a - x = amount left after decay process  

a) for completion of half life:

Half life is the amount of time taken by a radioactive material to decay to half of its original value.

Number of half lives =

Thus 3 half lives have taken place.

geosphere and hydrosphere.

this is because the geosphere has to do with geological events, while the hydrosphere controls all water on earth.

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