Bond strength follows this trend triple>double>single....Triple bonds have 2 pie bonds and 1 sigma bond, Double bonds have 1 pie bond and 1 sigma bond and single bonds have 1 sigma bond.

The bonds in CO2 are double bonds from C to O. The double bonds each have 1 sigma bond and 1 pi bond.

They have sigma and pi bonds

When you have one bond, it's a sigma bond.

When you have double bonds, you have 1 sigma and 1 pi bond

When you have a triple bond, you have 1 sigma and 2 pi bonds.

Ethylene has 4 single bonds (carbon to hydrogen) and 1 double bond (carbon to carbon).

A double bond consists of 1 sigma bond and 1 pi bond, and a single bond consists of 1 sigma bond. Between a sigma bond and a pi bond, a sigma bond is stronger due to it's shorter bond length, thus, a C=C bond is not twice as strong as a C-C bond.