Answer: It was obtained 8515 years ago
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) to find the rate constant:
Half life is the amount of time taken by a radioactive material to decay to half of its original value.


b) for completion of 36% of reaction


t = 8515 years
The time was 8515 years.
Freshwater marshes occur beside rivers and oceans.
Yes, this statement is true .
Freshwater marshes conatins fresh water . They are generally found near the river mouths. They are found along the fringes of lakes and rivers where the water table, the upper surface of underground water, is very high. Marshes are useful for the damage cause by the flood storing the water.
Answer: The pH scale measures whether there is more hydroxide or hydronium in a solution.
Is important because it tells you how basic or acidic the solution is.
Explanation: