Answer: 20 gallons of 16% and 8 gallons of 23% solution is usedfor 28 gallons of the 18 % solution.
Explanation:
According to the dilution law,
where,
= concentration of ist disinfectant solution = 16 %
= volume of pure acid solution = x gallons
= concentration of another disinfectant solution= 23%
= volume of another acid solution= (28-x) gallons
= concentration of resulting disinfectant solution = 18 %
= volume of resulting acid solution = 28 gallons

(28-x) = (28-20) = 8 gallons
Thus 20 gallons of 16% and 8 gallons of 23% solution is usedfor 28 gallons of the 18 % solution.
Answer:
• The Na atom is formed when the Na+ ion gains an electron.
• A Na+ ion has 10 electrons and a Na atom has 11 electrons.
• A sodium atom has one more electron shell than a sodium ion.
• A Na+ ion is formed when a Na atom loses an electron
PH is the scale of measurement to check either the solution is acidic or basic. if the pH value is greater than 7, the solution is towards basicity and if the pH value is less than 7, the solution is towards acidity.
pKa is the dissociation constant and it is used to describe the change in pH value, when pKa is equal to pH: 50% of the ionizable group is protonated and 50% of the enzymes will be active.
So 50% of the enzymes will be active.
The answer is; relative dating
Through relative dating, rock layers are able to be sequenced with regards to their ages relative to each other. This, therefore, does not determine the absolute age of the rock layers (absolute dating). Techniques used in relative dating include stratigraphy and biostratigraphy that determine which layer is older than the other. In absolute dating, methods employed are carbon-dating and radiometric dating.