Answer: no friction, metal
Explanation: yes
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.
In a study of the raw materials used for photosynthesis, the two molecules that would be studied are carbon dioxide and water. This is because they are the reactants of the process. Without these molecules the process of photosynthesis cannot happen.