Answer: 8.1 days
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 = x
a - x = amount left after decay process=
a) to find 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 one fourth of reaction



Thus after 8.1 days , one fourth of original amount will remain.
Answer:

Explanation:
Hello there!
In this case, according to the given information, it turns out possible for us to solve this problem by using the combined gas law due to the fact that we are dealing with variable volume, temperature and pressure:

In such a way, we solve for the final volume, V2, considering that the initial volume, V1, is 500 mL, the initial temperature, T1, is 273 K (STP), the initial pressure, P1, is 1 atm (STP) and the final temperature, T2, is 325 K and the final pressure, P2, is 125 kPa (1.23 atm):

Regards!