Which of the following is not a way that humus affects the properties of soil?
a. humus expands with increased moisture levels.
b. humus increases the movement of water and air in soil.
c. humus decreases the porosity of soil.
d. humus acts as the basis for soil life.

Use the drop-down menus to match each part of the scenario to the correct scientific practice. akira records the speed of a reaction without a catalyst and then with a catalyst. akira creates a reaction without a catalyst and repeats the reaction with a catalyst. akira turns in a written lab report to his science teacher. akira wonders, "will adding a catalyst speed up this chemical reaction? " akira writes in his notes that adding a catalyst sped up the chemical reaction because the catalyst lowers the activation energy needed to get the reaction started.