Would a full concert hall have different reverberation from an empty hall ? explain

Free runners jump long distances and land on the ground or a wall. how do they apply newton’s second law to lessen the force of impact?

Give one example to show that when substances are mixed,it may result in a chemical or a physical change depending on the conditions.

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