Pellets of calcium chloride are spread on a sidewalk covered in water that is 36°c. under which circumstance will the calcium chloride dissolve faster? it rains, increasing the amount of water on the sidewalk. sand is sprinkled on the sidewalk. the water cools to a temperature of 33°c. people walking on the sidewalk crush the calcium chloride pellets. the air pressure increases as the weather changes.

people walking on the sidewalk crush the calcium chloride pellets.

Explanation:

When calcium chloride pellets are crushed with feet it increases the surface area of the calcium chloride. As the surface area increase the number of collision between the reactant molecules increases. Here the reactant molecules are calcium chloride ions and water molecules. In the process of dissolution the calcium chloride ions get hydrated by the dipoles of the water molecules. As the frequency of collision increases it lowers the activation energy or threshold barriers to start a reaction.  

- aluminum and copper chloride.

- the chloride ion to separate the aluminum from the oxygen so that the aluminum can react with the copper ions (and the water molecules).

plants need sunlight, water, and carbon dioxide to make food. plants use the raw materials of water, nutrients they absorb from soil, and carbon dioxide to make sugars the plant can use. energy from the sun and chlorophyll are also needed.