Properties of Alkenes - Free MCQ Practice Test with solutions, NEET Chemistry

Option D is correct.

KMnO₄ solution (cold, dilute) reacts with ethene by oxidising the double bond to form a diol; the purple colour of potassium permanganate is lost and a brown precipitate of MnO₂ appears. Ethyne does not give this test under these conditions, so this test distinguishes the two.

Ammoniacal cuprous chloride solution reacts with a terminal alkyne such as ethyne to form a red precipitate of copper acetylide (Cu₂C₂). Ethene does not form this precipitate, so this test also distinguishes them.

Bromine water is decolourised by both ethene and ethyne by addition across the multiple bond; therefore it cannot be used to distinguish between them.

Because both 2 and 3 distinguish ethene and ethyne while 1 does not, the correct choice is Both 2 and 3 (option D).

Photochemical chlorination of alkane take place by free radical mechanism which are possible by Homolysis of C - C bond 

Option C is correct.

Reason: Protonation of an alkene leads to the carbocation that is thermodynamically more stable; the general stability order is tertiary > secondary > primary because of hyperconjugation and inductive effects.

The species in option C is a secondary carbocation (the positively charged carbon is bonded to two other carbon atoms). A secondary carbocation is more stabilized by more alkyl substituents that donate electron density by hyperconjugation and by the inductive effect, compared with primary carbocations.

Options B and D represent primary carbocations, and option A is a neutral alkane (not a carbocation). Therefore the carbocation shown in option C is the most stable among the choices.

Answer: Option C

CH₃ - CH= CH₂ + HOSO₂OH→CH₃—CH(OSO₂OH)—CH₃

Ethylene reacts with HBr to form Ethyl bromide. The reaction propagates as follow:-
H₂C=CH₂  +  HBr → H₂C+-CH₃ →H₂BrC-CH₃ 
Since π cloud is electron rich, so HBr dissociates into H⁺ and Br^-. H⁺ attacks on alkene to give a carbocation and then Br^- attacks to get ethyl bromide.

When propene on ozonolysis it yields a new structure called ozonide 
and there cleavage takes place and it yields two products namely 
1.acetaldehyde
2.formaldehyde

The reductive ozaonalysis of 2,3 -Dimethyl-2-butene yields acetone.The reaction is as follows: 2,3 -Dimethyl-2-butene acetone

Only the geminal dihalide will give a positive Tollens' test after treatment with NaOH.

In organic chemistry, an electrophilic addition reaction is an addition reaction where, in a chemical compound, a π bond is broken and two new σ bonds are formed. The substrate of an electrophilic addition reaction must have a double bond or triple bond.

Boiling point depends upon intermolecular interactions which over here is more in cis due to its net dipole moment . The dipole moment enables electronic interactions which hold molecules together . Trans 2-Butene has more symmetry thanits cis isomer which results in better packing and hence higher melting point .