1) a controlled experiment is one in which only a is changed.
2) a chemical bond formed by the sharing of electrons is bonding.
3) if a solution has a ph with a high concentration of hydrogen ions (h+) it is considered a(n) solution

1) variable  2) ionic bonding 3) basic solution

Explanation:

1) An experiment in which an observer tests a hypothesis by looking for changes brought on by alterations to a variable. In a controlled experiment, an independent variable is the only factor that is allowed to be adjusted, with the dependent variable as the factor that the independent variable will affect.

2) Ionic bonding is the complete transfer of valence electron(s) between atoms. It is a type of chemical bond that generates two oppositely charged ions.

3) A solution with a high number of hydrogen ions is acidic and has a low pH value, known as basic solution

the match duh

explanation:

4.) metal

"-the movement of carbon from the nonliving environment into living things and back to the environment

-carbon is the essential component of proteins, fats, and carbohydrates (which make up all organisms)

-carbon exists in air, water, and living organisms

-producers convert carbon dioxide in the atmosphere into carbohydrates during photosynthesis

-bacteria in the atmosphere cycles through the system in filtration units

-in cellular respiration, carbon is released back into the atmosphere as carbon dioxide

-some carbon is stored in limestone (forming one of the largest "carbon sinks" on earth)

-largest carbon reservoir on earth= limestone

-carbon stored in the bodies of organisms as fat, oils, or other molecules may be released into the soil or air when the organism dies

-this may form deposits of coal, oil, or natural gas (fossil fuels, which increased the atmospheric carbon dioxide)

-fossil fuels store carbon left over from bodies of organisms that died millions of years ago

-they are located in the surface of earth, deep within the earth and beneath the ocean floor."