Electron affinity is the energy released when an electron is accepted by a neutral atom forming a negative ion. Chlorine has the higher electron affinity because it readily accepts an electron to become more stable. On the other hand, sodium have to give up an electron to complete its valence shell.
Answer:At the molecular level, the pressure of a gas depends on the number of collisions its molecules have with the walls of the container. If the pressure on the piston is doubled, the volume of the gas decreases by one-half. The gas molecules, now confined in a smaller volume, collide with the walls of the container twice as often and their pressure once again equals that of the piston.
Explanation:

Now, balance the equation:


in gaseous state exist as a diatomic molecule.
Answer:
compound, but I could be wrong