Question

Propane, with the molecular formula C$_3$H$_8$ has :

• A. '6' Covalent bonds
• B. '7' Covalent bonds
• C. '10' Covalent bonds
• D. '8' Covalent bonds

Hint:

For alkanes with molecular formula C$_n$H$_{2n+2}$, the total number of covalent bonds (C-C and C-H) is $3n+1$. For propane (C$_3$H$_8$), $n=3$, so total bonds = $3(3)+1 = 9+1 = 10$.

Answer 1

The Correct Option is C

Step 1: Draw the structural formula of Propane (C$_3$H$_8$).
Propane is an alkane with three carbon atoms. The carbon atoms are bonded in a straight chain, and hydrogen atoms are attached to the carbon atoms. The skeletal structure is C-C-C.
Each carbon atom forms a total of four bonds.
The first carbon (terminal) is bonded to one other carbon and needs three hydrogen atoms.
The second carbon (middle) is bonded to two other carbons and needs two hydrogen atoms.
The third carbon (terminal) is bonded to one other carbon and needs three hydrogen atoms. The structure looks like this:

Step 2: Count the Carbon-Carbon (C-C) covalent bonds.
There are two C-C single bonds in the propane molecule. Step 3: Count the Carbon-Hydrogen (C-H) covalent bonds.
The first carbon has 3 C-H bonds.
The second carbon has 2 C-H bonds.
The third carbon has 3 C-H bonds.
Total C-H bonds = $3 + 2 + 3 = 8$ C-H bonds. Step 4: Calculate the total number of covalent bonds.
Total covalent bonds = (Number of C-C bonds) + (Number of C-H bonds) Total covalent bonds = $2 + 8 = 10$. Step 5: Compare with the given options.
(1) '6' Covalent bonds: Incorrect.
(2) '7' Covalent bonds: Incorrect.
(3) '10' Covalent bonds: This matches our calculated value.
(4) '8' Covalent bonds: Incorrect (this is just the number of C-H bonds). (3) '10' Covalent bonds