Answer
a) $2C_{2}H_{6} + 7O_{2} = 4CO_{2} + 6H_{2}O$
b) $2C_{3}H_{6} + 9O_{2} = 6CO_{2} + 6H_{2}O$
c) $2C_{2}H_{2} + 5O_{2} = 4CO_{2} + 2H_{2}O$
Work Step by Step
Hydrocarbon undergoes combustion reaction to produce Carbon dioxide and water. So, here for all equations the end products will be Carbon dioxide and water. Before balancing the equation, condensed structural formula can be written as molecular formula so that balancing will be easy. For example, $CH_{3}CH_{3}$ will be written as $C_{2}H_{6}$.After that, balancing will be done by putting number before each molecule, if necessary, so that the no. of atom for any atom will be same on both side.
