The most reactive hydrocarbon is : from Chemistry Hydrocarbons

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 Multiple Choice QuestionsMultiple Choice Questions

271.

Arrange the following in the decreasing order of their melting points:
I. Heptane      II. Octane
III. Nonane     IV. Decane

  • IV > II > III > I

  • IV > III > I > II

  • I > II > IV > III

  • II > III > I > IV


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272.

The most reactive hydrocarbon is :

  • methane

  • ethane

  • ethylene

  • acetylene


C.

ethylene

In ethylene H2C = CH2, the C - C bond distance is 1.34 Å, therefore, the π electrons of the double bond are easily exposed to the reactant (electrophiles) which readily react. In acetylene molecule HC  CH, although there are two π bonds but these electrons are not exposed to the attacking reagents due to small bond distance of C C bond (1.20 Å). A catalyst mercuric ion is therefore needed in reactions with actylene.


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273.

Which of the following is not a cumulated diene?

  • Hexa - 2 , 3 - diene

  • Penta - 1 , 3 - diene

  • Hexa - 1 , 2 - diene

  • Penta - 2 , 3 - diene


274.

What is the product P ?

  • Both (a) and (b)


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275.

In the eclipsed conformation of ethane, the dihedral angle between the hydrogen atoms of adjacent methyl groups is :

  • 60°

  • 120°

  • 180°


276.

The major product of the addition of water molecule to propyne in the presence of mercuric sulphate and dilute sulphuric acid is :

  • ethanal

  • 2-propanol

  • propane

  • propanone


277.

Which of the following statements is not an essential feature of an optically active molecule ?

  • It will rotate the plane of polarised light

  • It will have a non-superimposable mirror image

  • It will have no element of symmetry

  • It will have an asymmetric carbon atom


278.

The reagent which could distinguish between 1-hexyne and 1-hexene is :

  • Ag(NH3)2+

  • KMnO4

  • Br2 in CCl4

  • H2SO4


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279.

Choose the correct reagent required to carry out the transformation :

  • Zn + conc. HCl

  • conc. H2SO4

  • Li then H2O

  • H2/Pt


280.

The heat liberated when 1.89 g of benzoic acid is burnt in a bomb calorimeter at 25°C and it increases the temperature of 18.94 kg of water by 0.632°C. If the specific heat of water at 25°C is 0.998 cal/g-deg, the value of the heat of combustion of benzoic acid is

  • 881.1 kcal

  • 771.2 kcal

  • 981.1 kcal

  • 871.2 kcal


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