This video lecture from Group IIIA and Group IVA Elements (F.Sc. second year Chemistry) covers the occurrence of carbon and silicon. Carbon exists as carbonates in combined state while several crystalline and amorphous allotropes exist in free state including diamond, graphite, grapheme, fullerene, carbon nano tube (CNT), coal, charcoal and carbon black. Silicon exists in abundance in earth’s crust primarily in the form of silicates and doesn’t exist in free state. Find more e-learning material and educational video lectures in Urdu at maktab.pk. These videos are free to use for promotional and commercial purpose by keeping the credits to Maktab.