Question

The number of shared pairs of electrons in propane is
A. 2
B. 4
C. 6
D. 10

Answer 1

Hint: Propane is a three-carbon alkane.
An alkane has hydrogen and carbon atoms organized in a structure where carbon-carbon bonds are single.

Complete step by step solution:In this question, we have to find out the no.of shared pairs of electrons in propane.
We know that propane is an alkane.
Let us know about alkane first.
In organic chemistry, an alkane, or paraffin, refers to an acyclic saturated hydrocarbon.
We can say that an alkane is made up of hydrogen and carbon atoms organized in such a structure so that carbon-carbon bonds are single.
It has the general chemical formula\[{C_n}{H_{2n + 2}}\].
For n=1, methane (\[C{H_4}\]) exists.
In this compound, each carbon atom is sp3-hybridized having 4 sigma bonds, and each hydrogen atom is connected to one of the carbon atoms in a carbon-hydrogen bond.
The extended sequence of connected carbon atoms in a molecule is the carbon skeleton or carbon backbone.
Propane has four carbon atoms.
Its chemical formula is\[{C_3}{H_8}\].
There are three carbon atoms therefore there are two carbon-carbon bonds.
The rest of the valency is satisfied by hydrogen atoms.
First carbon is connected to three hydrogen atoms, second carbon to two H atoms, and third carbon to three H atoms.
So, there are 8 carbon-hydrogen bonds.
Bonds are nothing but shared electron pairs as this is a covalent compound.
So, the number of shared pairs of electrons in propane is 10.

So, option D is correct.

Note: Alkanes with more than three carbon atoms can be organized in different ways, constructing structural isomers.
The easiest isomer of an alkane is when the carbon atoms are organized in a single chain with no branches. This isomer is occasionally known as the n-isomer.