The correct answer is D. all above.
The color of the electrode will change from a light gray to a dark gray or black when the battery is fully charged. Gassing will also occur when the battery is fully charged. This is because the hydrogen and oxygen gases that are produced during the charging process are released from the battery. The specific gravity of the battery will also increase when it is fully charged. This is because the electrolyte in the battery will become more concentrated as it is charged.
Here is a more detailed explanation of each option:
- Color of electrode: The color of the electrode will change from a light gray to a dark gray or black when the battery is fully charged. This is because the lead sulfate crystals that are present on the electrode plates will dissolve as the battery is charged.
- Gassing: Gassing will also occur when the battery is fully charged. This is because the hydrogen and oxygen gases that are produced during the charging process are released from the battery. The gassing will be more pronounced if the battery is being charged at a high rate.
- Specific gravity: The specific gravity of the battery will also increase when it is fully charged. This is because the electrolyte in the battery will become more concentrated as it is charged. The specific gravity of the electrolyte can be used to determine the state of charge of the battery.
It is important to note that the battery should not be overcharged. Overcharging can damage the battery and shorten its lifespan.