21. true or false: during heat transfer heat always travels from the warmer object to the cooler object.

Which of the choices below is one of the primary gases found in the atmosphere? a. helium b. carbon dioxide c. nitrogen d. argon

Glass has a hardness that is in the middle of the hardness scale. what is the hardness of glass?

When is a current produced? when the terminals of an electrochemical cell are connected by a wire if the electric circuit is opened in an electrochemical cell if the electrolyte is removed from an electrochemical cell when the electrodes are reversed in an electrochemical cell