What are the following substances?

I) Tranquilizers are medicinal drugs taken to reduce tension or anxiety, e.g., Xanax, Valium.
II) A preservative is a substance or chemical added to products such as food, beverages, and many other products to prevent decomposition by microbial growth or undesirable chemical changes.
III) Synthetic detergent is any synthetic substance, other than soap, that is an effective cleanser and functions equally well as a surface-active agent in hard or soft water. It is a non-soap cleanser that exerts its effect by lowering the surface tension of an aqueous cleansing mixture, e.g., sodium p-dodecyl benzenesulphonate.