What will result if a burner manifold is not exactly perpendicular to the burner?

When a burner manifold is not perfectly perpendicular to the burner, it can lead to improper mixing of gas and air in the venturi, the part of the burner responsible for creating the right gas-air mixture for combustion. Specifically, if the alignment is off, the gas can bounce off the sides of the venturi instead of mixing correctly with air, which disrupts the intended flow dynamics.

This turbulence and improper mixing can result in incomplete combustion, often characterized by the presence of yellow flames instead of the desired blue flames. Blue flames indicate a good mix and complete combustion, while yellow flames usually suggest incomplete combustion, often leading to soot production and a less efficient burn. Thus, the outcome of misalignment of the burner manifold is the formation of yellow flames due to this disrupted gas flow and mixture, making this choice the accurate answer.