Answer:longitudinal design
Explanation: we need to know what is longitudinal design. By definition,
longitudinal design is the study of variables or group of variables which have similar cases and repeated over a long on short period of time. This cases happened between a similar group( teenage girls ), and it happened repeatedly over a long period of time, so this will require a longitudinal design.
Answer;
A.Vinegar and soda
Explanation;
-A salt is a substance that contains a cation which is a metal ion or an ammonium ion and an anion derived from an acid. It is an ionic compound that can be formed by the neutralization reaction of an acid and a base.
The current projects of the Environmental Protection Act is to reduce the carbon footprint in the atmosphere which is responsible for the climate changes.
<u>Explanation:</u>
Environmental protection act is working to reduce greenhouse gases in the year 2020. And its its energy use and the fuel consumption for climate change in the atmosphere.
Environmental protection act is the independent agency of the US federal government for the environmental protectio. It has the responsibility of maintaining and enforcing the national standards under the variety of environmental law.
Answer:

Explanation:
The pH scale stands for the power or potential of hydrogen. It measures how acidic or basic a solution based on the concentration of hydrogen ions and a scale from 1 to 14.
This scale is unique because it is logarithmic. So, every time the pH changes by 1 on the scale, the actual concentration of the solution increases or decreases by a tenfold.
So, a solution with a pH of 7 is ten times more acidic than a solution with a pH of 8. This can be translated to:

The black coffee has a pH of 5 and the hand soap has a pH of 10. We want to find how many times more acidic coffee is, so we subtract 5 from 10 and get 5. The difference in pH is 5.

Coffee is <u>10⁵ or 100,000 times more acidic than hand soap.</u>