All India Engineering / Architecture Entrance Examination (AIEEE)

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AIEEE 2009 Chemistry

Q. 27. Using MO theory predict which of the following species has the shortest bond length?

Sol: The bond order of , , and is 1, 3, 2.5 and 1.5 respectively. Since, has highest bond order, so it has shortest bond length.

Answer: (2)

Q. 28. A binary liquid solution is prepared by mixing n-heptane and ethanol. Which one of the following statements is correct regarding the behaviour of the solution?

1. n–heptane shows +ve deviation while ethanol shows –ve deviation from Raoult’s Law.
   
   
2. The solution formed is an ideal solution.
   
   
3. The solution is non-ideal, showing +ve deviation from Raoult’s law.
   
   
4. The solution is non-ideal, showing –ve deviation from Raoult’s Law.

Sol: When n–heptane is added to ethanol, the H-bonding interaction between ethanol molecules is loosened, so weaker interaction among molecules leads to higher vapour pressure. Thus, it forms a non-ideal solution with positive deviation from Raoult’s law.

Answer: (3)

Q. 29. The alkene that exhibits geometrical isomerism is:

1. 2–methyl–2–butene
   
   
2. propene
   
   
3. 2–methyl propene
   
   
4. 2–butene

Sol: Terminal alkenes never show geometrical isomerism and non–terminal alkene with 2 different groups attached to each atom having restricted rotation is capable of showing geometrical isomerism.

Answer: (4)

 Q. 30. Which of the following has an optical isomer?

Sol: Square planar complexes can not show optical isomerism. So, option (2) and (3) are ruled out. Compound in option (4) i.e. has a plane of symmetry, so it is also optically inactive.

Answer: (1)