Answer :
The parent and daughter concentrations (in percentages) is, 60 % and 40 % respectively.
The age of rock is
Explanation :
First we have to calculate the parent and daughter concentrations (in percentages).
and,
As we know that, the half-life of uranium-238 = years
Now we have to calculate the rate constant, we use the formula :
Now we have to calculate the time passed.
Expression for rate law for first order kinetics is given by:
where,
k = rate constant =
t = time passed by the sample = ?
a = initial amount of the reactant = 3 g
a - x = amount left after decay process = 1.8 g
Now put all the given values in above equation, we get
Therefore, the age of rock is