Why do spring balances show reading After long use

When you push downward on a book at rest on a table, you feel an upward force. does this force depend on friction? defend your answer.

If the chemical properties of a substance remain unchanged and appearance or shape of a substance changes it is called a ?

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