3) In hardware design, a prototype is a hand-built model that represents a manufactured (easily replicable) product sufficiently for designers to visualize and test the design. The word prototype comes from the Latin words proto, meaning original, and typus, meaning form or model.
In chemistry, a salt is an ionic compound which is made up of two groups of oppositely charged ions. The ion with a positive charge is called a cation, and the one with a negative charge is called an anion.
Common salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in its natural form as a crystalline mineral is known as rock salt or halite. Salt is present in vast quantities in seawater, where it is the main mineral constituent. The open ocean has about 35 grams (1.2 oz) of solids per litre, a salinity of 3.5%. Salt is essential for human life, and saltiness is one of the basic human tastes.