An air conditioning unit turns off once it reaches its goal temperature. The house warms up and the air conditioning unit turns on again. When the air conditioning unit turns on, it is an example of:

A)input

B)process

C)output

D)feedback

D) feedback.

Explanation:

An air condtioning unit consists of the following elements according to available choices:

Inputs: Refrigerant, air from surroundings, electricity.

Process: Refrigeration cycle.

Output: Conditioned air at goal temperature.

Feedback: Activation and deactivation of the air conditioning unit depending on indoor temperature.

When the air conditioning turns on and off to keep goal temperature indoors, a control stage consisting in a controller and a action element is acting to reverse the behavior of the process with a view to keep goal temperature.

Hence, correct answer is D.

chemical digestion occurs in the stomach were hcl and pepsin forms chyme, the mouth in which salivary amylase breaks down starch to form bolus, and the small intestine specifically the duodenum.

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.