Test: Alkanes : Preperation and Projections - JEE MCQ

To decide the structure of alkene that undergoes ozonolysis, bring the products together in such a way that O atoms are face to face, and replace O by double (=) bond. Thus,

C = O is (EWG) hence π electron transfer is onwards ring.

Nature of halogen atom and the alkyl group both determine rate of reaction.

2,5 dimethyl hex -3-ene on reductive ozonolysis in presence of O₃ and Zn/H₂O, gives 2 moles of 2-methyl propanal.

Hence, the correct option is (c).

The heat of hydrogenation of an alkene depends upon its stability. Higher the stability, lower the heat of hydrogenation. Since CH₂ = CH₂ has no substituent, it is the least stable alkene and hence has the highest heat of hydrogenation

Addition reaction occurs on a double bond. The compound containing double bonds are also undergo polymerisation. So, the correct option are both (i) and (iv) e.g.

(addition reaction)

When 3-methyl-2-pentene is reacted with hypochlorous acid, the product formed is 2 -chloro-3-methyl pentanol-
3 The reaction obeys Markovnikov's addition and the hydroxide and chloro group is added across the double bond of two carbons.
We can write the reaction of 3 -methyl-2-pentene with HOCl as,

This is an example of Hofmann elimination which generally takes place by E2 mechanism and the latter requires a strong base (recall that OH^- is a strong base than I^-). The NH₂^-, being a strong base can't be eliminiated easily.

Free rotation around carbon-carbon bond takes place easily in alkanes. Now ethane and hexachloroethane both are alkanes, but in hexachloroethane bulky chlorine atom is present while ethane is least hindered.

OsO₄ results in syn addition of 2 "OH" group.

Dihydroxylation reaction of alkene.