What are the practical uses of a theory?

Is an element composed of only one type of element? What is the empirical formula for Ba an S? What quantity can tell you weather a solution acidic or basic? Elements in the third row of the periodic table or lower can have octets? When haemoglobin molecule combines with oxygen the substance is called? Why Shouldn't every sample of matter have a negative charge Since all atoms have negatively charged electrons? What does neon look like at room temperature? What equals 0.01 g? How do you get deodorant stains out of white t shirts? Why beta glucose is more stable than alpha? What color does Litmus paper turn when dipped in cranberry juice? How are erasers made? What kind of forces act between molecule? What is the balanced equation of zinc oxide and sulphuric acid? What is a spontaneous endothermic reaction? What is the principle of an ozone generator? What are some chemical properties of xenon? How many moles are equal to 9.03 x 1024 atoms of mercury hg? What type of burn causes arc injuries and flash burns? Why does baking soda and coke create a chemical reaction?

What are the practical uses of a theory?