The geosphere refers to the

crust
mantle
core
all of the above, at the same time.

Hector is back from his morning run and is feeling light-headed because his energy is depleted which food item will provide him with a quick source of carbohydrates

In the practice of science, this type of reasoning is used to develop explanations.

Consider the following reaction: 2h2 + o2 —> 2h2o a) what are the reactants in this reaction? b) what are the products in this reaction? c) how many molecules of oxygen are used in this reaction?