(a) Allotropy: Allotropy is defined as the phenomenon due to which an element exists in two or more forms in the same physical state with identical chemical properties but with different physical properties.
(b) Carat – The weight of diamond is expressed in carats [ 1 carat = 0.2 g]
(c) Crystal – A crystal is a homogeneous solid which particles (atoms, molecules or ions) are arranged in a difinite pattern due to which they have definite geometrical shape with plane surfaces e.g. sugar and sodium chloride.
(d) Catenation – The large number of organic compounds is due to the ability of carbon atom to form long chains with other carbon atoms through the sharing of electrons. This unique property of carbon is known as catenation.
