What is the defining characteristic of a closed system in the context of a chemical experiment?

The temperature and pressure inside the system are held constant.

Energy, such as heat and light, is not allowed to enter or exit the system.

The reaction is visible and can be observed from the outside at all times.

Matter, such as atoms and molecules, cannot enter or leave the system.

A student burns a piece of wood in a campfire and notices the pile of ash left over is much lighter than the original piece of wood. Why does this not violate the law of conservation of mass?

The law of conservation of mass only applies to reactions in liquids, not to burning solids.

The campfire is an open system, and gaseous products like smoke and carbon dioxide escaped.

A large amount of matter was converted directly into heat and light energy during the fire.

The intense heat of the fire destroyed many of the atoms that made up the wood.

The mass will decrease because liquid water is less dense than solid ice.

The mass will increase because energy from the room enters the jar.

The total mass will remain exactly the same.

The mass will first decrease as it melts and then increase as it warms up.

The mass of the oxygen gas in the jar decreases by an equal amount as it is consumed in the reaction.

The increase in the solid's mass is an illusion caused by the heat of the reaction affecting the scale.

The law of conservation of mass does not apply when there is a change of state from gas to solid.

The jar is not a truly closed system, and air leaks in to balance the mass.

To prevent any gases produced or consumed during the reaction from escaping and affecting the total mass measurement.

To increase the pressure within the container, which forces the reaction to happen more quickly and efficiently.

To ensure the temperature stays perfectly constant, as temperature changes can alter the mass of atoms.

To protect the reactants from being contaminated by microorganisms or dust particles present in the outside air.