A teacher demonstrates, in a fume cupboard, two experiments to show the movement of particles.
In the first experiment, she places some red-brown bromine vapor at the bottom of a gas jar. She then places another gas jar containing colorless nitrogen gas on top of it, as shown in the diagram.
Choose two statements that are correct about this experiment:
In the second experiment, she soaks two pieces of cotton wool in different liquids and places them at opposite ends of a glass tube. She immediately seals the tube with bungs.
During the experiment, a white ring of ammonium chloride appears in the tube.
State whether the white ring appears at P, Q, or R.
Explain your choice.
