The is a measure of how acidic or basic a solution is.

The correct answer is pH.

Explanation:

The pH is a measure that is used to determine the acidity or alkalinity of a substance.

Its acronym is for hydrogen potential or hydrogenation potential.

It can be measured through a potentiometer or pH meter, which measures the potential difference between reference electrodes and glass electrodes that are sensitive to hydrogen ion.

It is a very important procedure and widely used in chemistry and biochemistry, since it determines many significant characteristics of the structure and activity of the molecules.

d. stage 4

explanation:

the existence of some kind of demographic transition is widely accepted in the social sciences because of the well-established historical correlation linking dropping fertility to social and economic development.[1] scholars debate whether industrialization and higher incomes lead to lower population, or whether lower populations lead to industrialization and higher incomes. scholars also debate to what extent various proposed and sometimes inter-related factors such as higher per capita income,lower mortality, old-age security, and rise of demand for human capital are involved.[2]