Jerry prefers to burn bituminous coal in his fireplace because of the yellow flame. what causes that flame color?

Bitumionous coal burns with yellow flame because of the incomplete combustion of the hydrocarbons in it. The color of flame indicate the combustion of the hydrocarbon contain of the substance. Normally a blue flame indicate complete combustion of the substance releasing carbon dioxide.
However in case of incomplete combustion, which happen due to poor supply of oxygen, causes yellow flame and shoot. In incomplete combustion, carbon monoxide and carbon are released.

Also due to different impurities contained in Bituminous coal,like sulfur, it burns with yellow flame.

Answerthis solution will not form a precipitateexplanationsolubility equilbrium:         pbf₂(s)  ⇄ pb²⁺(aq) + 2 f⁻(aq)the solubility product expression is    (we exclude solids from the equilibrium expression).now suppose we have the trial ion product q, which we can define as    then, we can interpret  q as the product of the concentration of the ions that we have and ksp as the product of the ion concentrations that are needed to form a saturated solution.if q > ksp, then that implies that there will be a surplus of ions that exceed the amount that is required to form a saturated solution. a precipitate will then form (the precipitate continually  forms until the surplus ions are removed and q is decreased to ksp's value).if q = ksp, the saturated solution that forms is barely saturated and the precipitate will be minimal.if q < ksp, then the ion concentration will not be enough to form a saturated solution (so no precipitate).using our information, we calculate the trial ion product:     since q = 2.7  × 10⁻⁸ < ksp =  4  ×  10⁻⁸, a precipitate will not form.