Which air gap indicates suitable backflow protection from a sink in domestic or industrial premises?

When testing the effectiveness of an antiobiotic what does the zone of inhibition represent? What effects does coke have on people? What happened with the anacharis and the test tubes of water? Do plants get energy from their green leaves? What would you expect to find if you measured the temperatures of rocks on the ocean floor at various distances from a mid-ocean ridge? How do you dye your hair black if your hair is blonde? What is an atom called when it has a charge? Which particles do plants absorb to obtain energy? What alkali metal has the biggest radius? What is cost of removal of clamp? Where is active telomerase found in? What is the name of a knife edged ridge between two corries? Is silcon a metal? What function did coffering perform? What type of compounds can be used with water to hydrolyze triacylglycerols? What is the cardinal rose in Mexico? What is the purpose concerning clinical pathway? What kind of organism is oscillatoria? What are all the body layers called? What properties are given to the metal by the strong attraction between the delocalised electrons and the metal ions?