Kate gathered three boxes of the same size made of different materials: glass, clear plastic, and aluminum painted black. she placed them on a window sill in the sun for an hour then measured the warmth of the air in each box. in this experiment, the warmth of the air is a( a. independent variable b. control c. dependent d. constant

In the given experiment there are three factors

a) type of material : these are independent of each other so are independent variable

b) time : one hour : we have a fixed time so this a constant

c) warmth of air : it is dependent on the time and also on the material of the boxes taken for keeping the air in sun. Thus answer is "Dependent"

I am sure that the answer is C dependent

A reversible reaction is one where B) there is little change in the net free energy between substrate and product.

Explanation:

A reversible reaction is one that reagents are transformed into products and at the same time products are transformed into reagents. That is to say that as the products appear in the reaction, they can react with each other by regenerating the reagents again. It is represented by a double arrow, indicating that the reaction can be carried out both in one direction and the other way around.

At the start of the reaction, there is a large amount of reagents. As time goes by, that amount decreases and speed too.

On the other hand, at the beginning of the reaction there are no products. As the reaction happens, the products are being formed and their speed will increase to match the speed of the reagents. When the rates of products and reagents are equal and constant, it is possible to say that the reaction is in chemical equilibrium. At this point, both reactions continue to happen, but the total concentrations of reagents and products no longer change.

The Gibbs free enthalpy or free energy of a system is a measure of the amount of usable energy (energy that a job can perform) in that system.

When a reaction system is in chemical equilibrium, it is in the lowest possible energy state (it has the lowest possible free energy). If a reaction is not in equilibrium, it will move spontaneously towards it because that allows it to reach a state of lower and more stable energy. Then when the reaction moves towards equilibrium, the free energy of the system decreases more and more.

Finally, a reversible reaction is one where B) there is little change in the net free energy between substrate and product.