1
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.
2
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.
3
MCQ (Single Correct Answer)

AIPMT 2005

The correct order in which the O $$-$$ O bond length increases in the following is
A
O2 < H2O2 < O3
B
O3 < H2O2 < O2
C
H2O2 < O2 < O3
D
O2 < O3 < H2O2

Explanation

Bond lengths of O $$-$$ O in O2 is 1.21 Å, in H2O2 is 1.48 Å and in O3 is 1.28Å. Therefore, correct order of the O $$-$$ O bond length is H2O2 > O3 > O2 or O2 < O3 < H2O2
4
MCQ (Single Correct Answer)

AIPMT 2004

In BrF3 molecule, the lone pairs occupy equatorial positions to minimize
A
lone pair - bond pair repulsion only
B
bond pair - bond pair repulsion only
C
lone pair - lone pair repulsion and lone pair - bond pair repulsion
D
lone pair - lone pair repulsion only.

Explanation

Lone pair - Lone pair repulsion > lone pair - bond pair repulsion > bond pair-bond pair repulsion.

The lone pairs of electrons are arranged on equatorial position as they are at maximum distance at these positions and hence they have minimum repulsion at these positions.

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