Question

Which of the following is not a chemical test to distinguish unsaturated hydrocarbons from saturated hydrocarbons.
A.Flame test
B.Bromine water test
C.Both of them
D.None of these

Answer 1

Organic compounds which have a double or a triple bond between two carbon atoms are known as unsaturated hydrocarbons. On the other hand the compounds which have only a single bond between carbon atoms are known as saturated hydrocarbon. We will check the behavior of the compounds with the substances in the options.

Complete step by step answer:
The first option given is flame test.
A flame test is an analytical procedure used in chemistry to detect the presence of certain elements, primarily metal ions, based on each element's characteristic emission spectrum. The color of flames in general also depends on temperature.
Saturated hydrocarbons burn in air with bright blue flame whereas unsaturated hydrocarbons burn in air with sooty yellowish flame, because saturated compounds contain less percentage of carbon which easily oxidised completely in air but unsaturated compounds need more oxygen for complete burning which is not present in air.
So we can easily distinguish by using this test.
The next option given is bromine water.
Bromine water is a brown colored liquid.
Unsaturated compounds give addition reactions with bromine water and decolorize it but saturated compounds do not give addition reactions. Hence they can distinguish by flame test as well as by bromine water test.
So bromine water can also be used to distinguish.
So the both the options are correct
The correct option is C. Both of them.

Note:
We used the reaction to find the answer to this question. It should be noted that flame tests are also used to distinguish alkali metals as they produce distinctive colors to the flames. When these elements are heated their electrons are excited and a particular wavelength of light is emitted which comes in the visible range.