what is the diffrence between a system and industries. its a grade science question i need it fast. thanks

Which is an example of a reversible physical change?

How is the use of hydroelectric power related to the sun

Use the drop-down menus to label each of the following changes p for physical change and c for chemical change. the substance changes to a new substance. the original substance can be recovered. the color changes. gas is produced and given off. the substance changes size, shape, or volume.