1
MCQ (Single Correct Answer)

AIPMT 2006

Which of the following is not a correct statement?
A
Multiple bonds are always shorter than corresponding single bonds.
B
The electron-deficient molecules can act as Lewis acids.
C
The canonical structures have no real existence.
D
Every AB5 molecule does in fact have square pyramid structure.

Explanation

AB5 molecule has generally trigonal bipyramidal structure. Sometimes due to presence of lone pair of electrons the structure gets distorted.
2
MCQ (Single Correct Answer)

AIPMT 2005

The correct sequence of increasing covalent character is represented by
A
LiCl < NaCl < BeCl2
B
BeCl2 < LiCl < NaCl
C
NaCl < LiCl < BeCl2
D
BeCl2 < NaCl < LiCl

Explanation

As difference of electronegativity increases % iconic charecter increases and covalent charecter decreases i.e, electronegativity difference decreases covalent charecter increases. Further greater the charge on the cation more will be its covalent character. Be has maximum (+2) charge.
3
MCQ (Single Correct Answer)

AIPMT 2005

The surface tension of which of the following liquid is maximum ?
A
C2H5OH
B
CH3OH
C
H2O
D
C6H6

Explanation

Hydrogen bonding in H2O > C2H5OH > CH3OH

Hence, H2O has maximum surface tension.
4
MCQ (Single Correct Answer)

AIPMT 2005

Which of the following molecules has trigonal planar geometry?
A
BF3
B
NH3
C
PCl3
D
IF3

Explanation

IF3 has three bond pairs and two lone pairs, thus, it has sp3d hybridization.



PCl3 has three bond pairs and one lone pair thus, it has sp3 hybridization.



NH3 has three bond pairs and one lone pair thus, it has sp3 hybridisation.


BF3 has three bond pairs and no lone pair thus, it has sp2 hybridisation.

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