Visitors Online: 1749 | Tuesday 30th September 2014
REGISTRATION
Find Friends Online

All India Engineering / Architecture Entrance Examination (AIEEE)

CBSE Guess > AIEEE > AIEEE Papers > 2009 > Chemistry

AIEEE 2009 Chemistry

 Q. 15. The two functional groups present in a typical carbohydrate are:

  1. –OH and –CHO

  2. –OH and –COOH

  3. –CHO and –COOH

Sol.:   Carbohydrate is a polyhydroxy aldehyde or polyhydroxy ketone or any compound which give these on hydrolysis. group includes aldehydic as well as ketonic group.

Answer : (4)

Q. 16. Calculate the wavelength (in nanometer) associated with a proton moving at

  1. 14.0 nm

  2. 0.032 nm

  3. 0.40 nm

  4. 2.5 nm

Sol:

Answer: (3)

Q. 17. The bond dissociation energy of B–F in BF3 is 646 kJ mol–1 whereas that of C–F in CF4 is 515 kJ mol–1. The correct reason for higher B–F bond dissociation energy as compared to that of C–F is

  1. lower degree of  interaction between B and F in BF3than that between C and F in CF4.

  2. smaller size of B atoms as compared to that of C atom.

  3. stronger  bond between B and F in BF3 as compared to that between C and F in CF4

  4. significant  interaction between B and F in BF3 whereas there is no possibility of such interaction between C and F in CF4 .

Sol: Boron in BF3 has a vacant p–orbital, allowing  back bonding while carbon in CF4 has no vacant orbital, so no back bonding is feasible. Thus, B–F bond is stronger than CF4.

Answer: (4)