Question

An element which is tetravalent and forms the basis of organic chemistry is:
(A) Carbon
(B) Hydrogen
(C) Iron
(D) Phosphorous

Answer 1

To answer this question, you must recall the element that forms the backbone of organic compounds and is the fundamental unit of organic chemistry. A tetravalent element is one which has a valency of four or the one which can form four covalent bonds.

Complete step by step solution:
Organic chemistry is the branch of chemistry which deals with organic compounds. These compounds are present in abundance in almost all living plants, animals and humans. Most of the organic compounds are hydrocarbons. The most abundant elements in organic compounds are carbon and hydrogen. Other elements that are commonly found in organic compounds are oxygen, nitrogen, chlorine, etc.
The basis for organic chemistry is carbon. It forms the backbone of all organic compounds due to the high stability of the carbon- carbon bond. Carbon has an atomic number 6 and it is present in the group 14 of the modern periodic table. It has four valence electrons in its valence shell, 2 in the s- orbital and 2 in the p- orbital. One electron from the s- orbital is excited to the p- orbital and thus, the valency is extended to 4 due to the presence of four unpaired electrons. Due to its tetravalency, carbon has the tendency to bond to a number of elements and form a variety of compounds.
The correct answer is A.

Note:
Carbon is the first element of the group 14 and thus it has no d- orbitals available. As a result carbon is small in size and cannot form complexes. It has a tendency to bind with fellow carbon atoms and form long chains. This property is known as catenation and is responsible for carbon being the essential constituent of the majority of organic compounds.