I see that the questions you've posted are not clear and seem to be jumbled together. I'll address each question separately to provide a clear and concise answer:
1. The only metal found in a liquid state at room temperature is Mercury (D). Mercury remains in liquid form at room temperature due to its low melting point.
2. Aquatic animals respire with the aid of gills (C). Gills are respiratory organs that allow aquatic animals to extract oxygen from water.
3. A renewable source of energy is the Sun (B). Solar energy from the Sun is considered renewable as it is continuously available and does not deplete natural resources.
4. Carbon (IV) oxide is added to the air through all processes except photosynthesis (A). During photosynthesis, plants absorb carbon dioxide from the air and release oxygen.
For the other questions, the options provided seem to be mixed up and unclear. If you can provide the questions in a more organized manner, I'll be happy to help with each one individually.
