How can light be emitted from an atom in ground state

When electrons absorb energy they are able to move from their ground states up to excited states. An example of this is when you light a match. The molecules of the matchstick are in its ground state. When you flick it on the ground or anything hard, it causes its molecules to move into the excited state and thus causing fire.

the volume of fluid displaced would equal the volume of the gas. use a gas syringe - this is a laboratory instrument that can be used to withdraw a certain volume of gas from a closed system or to measure the volume of gas from a chemical reaction.

the answer would be c