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NEET 2026
Exam
NEET
Year
2026
Subject
Chemistry
Chapter
Chapter

NEET 2026 · Chemistry · Chapter

The skeletal structure of a cyclic hydrocarbon is shown in the...

The skeletal structure of a cyclic hydrocarbon is shown in the figure above. Which of the following is the correct
The skeletal structure of a cyclic hydrocarbon is shown in the figure above.

Which of the following is the correct observation when this compound is shaken with aqueous bromine (Br_2/H_2O)atroomtemperatureintheabsenceoflight?) at room temperature in the absence of light?

Options

  1. AThe reddish-brown colour of the solution is rapidly decolorized due to an addition reaction.
  2. BA white precipitate of a polybrominated derivative is immediately formed.
  3. CThe reddish-brown colour of the bromine water remains unchanged.
  4. DThe solution turns colourless with brisk effervescence of hydrogen bromide gas.

Correct answer

C. The reddish-brown colour of the bromine water remains unchanged.

Step-by-step solution

The skeletal structure shown in the figure represents cyclohexane, which is a saturated cyclic hydrocarbon (cycloalkane).

Aqueous bromine (Br_2/H_2O),alsoknownasbrominewater,isareddish−brownsolutioncommonlyusedtotestforunsaturation(presenceofcarbon−carbondoubleortriplebonds).Unsaturatedcompoundsundergorapidelectrophilicadditionreactionswithbromine,causingthereddish−browncolourtodecolorize.<br><br>Sincecyclohexaneisasaturatedcompoundcontainingonlysinglebonds,itdoesnotundergoadditionreactions.Furthermore,intheabsenceoflight(UVradiation)orheat,freeradicalsubstitutionreactionswithalkanesdonotoccur.<br><br>Therefore,therewillbenoreactionbetweencyclohexaneandaqueousbromineunderthegivenconditions,andthereddish−browncolourofthebrominewaterwillremainunchanged.<br><br>Answer:Thereddish−browncolourofthebrominewaterremainsunchanged.), also known as bromine water, is a reddish-brown solution commonly used to test for unsaturation (presence of carbon-carbon double or triple bonds). Unsaturated compounds undergo rapid electrophilic addition reactions with bromine, causing the reddish-brown colour to decolorize.<br><br>Since cyclohexane is a saturated compound containing only single bonds, it does not undergo addition reactions. Furthermore, in the absence of light (UV radiation) or heat, free radical substitution reactions with alkanes do not occur.<br><br>Therefore, there will be no reaction between cyclohexane and aqueous bromine under the given conditions, and the reddish-brown colour of the bromine water will remain unchanged.<br><br>Answer: The reddish-brown colour of the bromine water remains unchanged.
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