Answer: 29.0 years
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.


b) for decomposition of 80 % of reactant



The age of a suspected vintage wine that is 20 % as radioactive as a freshlybottled specimen is 29.0 years
The solution with the lowest pH would mean that it is an acid, specifically a strong acid which completely dissociates into ions in aqueous solution. Among the choices listed above, I think the correct answer is option D. It is nitric acid that will have the lowest pH because it is the only strong acid in the group.
For answering for the question, there exists four choices:
1) Na+ + e- -------------- Na
2) Na --------Na+ + e-
3) Cl2 + 2e- ------------ Cl-
4) 2Cl- ---------Cl2 + 2e-
reduction half-reaction general formula is
oxidant + e - or + -------- Product
so in our case the answer is
1) Na+ + e- -------------- Na (exactly balanced)
Because some atoms<span> are more stable when they </span>gain or lose<span> an </span>electron<span> and </span>form ions<span>.</span>