Ionic compound is the answer!
Color is the least reliable
Once you have stopped for a school bus, do not pass until the driver signals you to proceed, the red lights stop flashing, or the bus starts moving ahead. Whenever a vehicle ahead of you stops to let a pedestrian pass in front of you, you should stay in line and until the vehicle ahead proceeds.
Photsynthesis to make food
It's G, since plants need carbon dioxide to perform photosynthesis