One (or more) of the following is (are) True for Incomplete combustion:a.Dissociation is a method to prevent incomplete combustionb.It can be caused by poor air fuel mixingc.High temperature is needed to prevent incomplete combustiond.It can be caused by insufficient amount of oxidizer or rich combustion

The statements that are true for incomplete combustion are:

b. It can be caused by poor air fuel mixing: This is true because for complete combustion to occur, the fuel and air (oxygen) need to be thoroughly mixed. If the mixing is poor, some fuel might not come into contact with oxygen and thus, not burn completely, leading to incomplete combustion.

d. It can be caused by insufficient amount of oxidizer or rich combustion: This is also true. Incomplete combustion can occur if there is not enough oxygen (oxidizer) for the amount of fuel present. This is often referred to as a 'rich' combustion condition, where the fuel to oxygen ratio is high. In such cases, not all of the fuel can react with oxygen, leading to incomplete combustion.

On the other hand,

a. Dissociation is a method to prevent incomplete combustion: This is not necessarily true. Dissociation is a process where a compound breaks down into two or more simpler substances, and it doesn't directly prevent incomplete combustion.

c. High temperature is needed to prevent incomplete combustion: This is also not necessarily true. While high temperatures can help to ensure that a reaction goes to completion, they are not the only factor. The availability of oxygen and the mixing of fuel and oxygen are also important.