When frozen carbon dioxide (CO2) is heated, it changes directly into a gas. Which statement BEST indicates that a physical change has taken place?
a. Heat caused an increase in gas production.
b. Heat caused a new substance to form.
c. Heat caused a decrease in energy.
d. Heat caused a change in state.

the water is warmed up by the sun and then it evaporates into the atmosphere. the sunlight warms the water by its heat. water is then cooled down and condensation takes place. the water then finally returns back to the earth by the process of precipitation in the form of rain or ice.

explanation:

light dependent reactions:

light independent reactions:

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stimulus is a change in the environment that causes an organism to react. the response is the reaction to the stimulus. some examples of stimuli for zebras are drought, to many predators, and bad feeding grounds such as dead grass or plants. zebras respond to stimuli just like all other living organisms