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.
Salt (sodium chloride) is made from positive sodium ions bonded to negative chloride ions. Water can dissolve salt because the positive part of water molecules attracts the negative chloride ions and the negative part of water molecules attracts the positive sodium ions. The amount of a substance that can dissolve in a liquid (at a particular temperature) is called the solubility of the substance.