C. How many grams of NaOH (sodium hydroxide) are necessary to make 100
mL of an 18% NaOH solution?

18 g

Explanation:

Remember that 1g is equivalent to 1 ml;

1g = 1 mL

100 g = 100 mL

Therefore in an 18% NaOH solution,  for every 100 mL, there is 18 g of dissolved NaOH. This is how we derive the percentage solution;

18 g / 100 g = 18%

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."