I believe this battery is called Sheet battery.
Sheet battery is a flexible, ultra thin energy storage and production device formed by combining nano tubes with a conventional sheet of cellulose based paper. It acts as both a high-energy battery and super-capacitor, combining two components that are separate in traditional electronics.
1.add the amount of the diagram which is M+Y then dived the answer you get.
The correct answer among all the other choices is 4. This is the number of the lowest energy level that contains an f sublevel. Thank you for posting your question. I hope that this answer helped you. Let me know if you need more help.
When atoms bond together they make molecules.
all the best