Question

In an electron dot diagram of propane (C3H8), how many double bonds are present?

Answer 1

Answer : The number of double bonds present in propane is, Zero.

Explanation :

Lewis-dot structure : Lewis-dot structure shows the bonding between the atoms of a molecule and also shows the unpaired electrons present in the molecule.

Carbon has '4' valence electrons and hydrogen has '1' valence electrons.

The total number of valence electrons in $C_3H_8$ = 3(4) + 8(1) = 20

In the given molecule propane, there is a single bond present between the carbon-carbon atom and carbon-hydrogen atom.

According to the Lewis-dot structure, the number of double bonds present in propane is, Zero.

The Lewis-dot structure is shown below.

Answer 2

Answer:- none

Explanations:- For naming hydrocarbons we use the suffix -ane, -ene and -yne.

-ane is used when we have only single bonds between all carbons. -ene is used if there is any double bond between two carbons and the -yne is used if there is any triple bond between two carbons.

The given name of the compound is propane. It ends at -ane and so it's an alkane and must have single bonds between all the carbons it has. So, there are zero double bonds present in $C_3H_8$ .

This is also clear from the below lewis dot structure of the compound.