Question

Identify the correct orders against the property mentioned:
A. H$_2$O $>$ NH$_3$ $>$ CHCl$_3$ - dipole moment
B. XeF$_4$ $>$ XeO$_3$ $>$ XeF$_2$ - number of lone pairs on central atom 
C. O–H $>$ C–H $>$ N–O - bond length 
D. N$_2$>O$_2$>H$_2$ - bond enthalpy 
Choose the correct answer from the options given below:

• A. B, D only
• B. A, C only
• C. B, C only
• D. A, D only

Hint:

The dipole moment increases with the difference in electronegativity and the molecular geometry. Lone pairs on the central atom increase as we go from simpler molecules like XeF\(_2\) to more complex ones like XeF\(_4\).

Answer 1

The Correct Option is C

Let’s evaluate each property and its respective order: - A. H\(_2\)O $>$ NH\(_3\) $>$ CHCl\(_3\) (Dipole Moment): - Water (H\(_2\)O) has the highest dipole moment due to its bent structure and high electronegativity difference between oxygen and hydrogen.
- Ammonia (NH\(_3\)) also has a dipole moment, but it is less than water due to the smaller electronegativity difference and less angular geometry.
- CHCl\(_3\) has the least dipole moment because the presence of chlorine atoms leads to a more symmetrical distribution of charge despite having polar bonds.
Therefore, A is correct.
- B. XeF\(_4\)>XeO\(_3\)>XeF\(_2\) (Number of Lone Pairs on Central Atom):
- XeF\(_4\) has the largest number of lone pairs on the central xenon atom (2 lone pairs).
- XeO\(_3\) has 1 lone pair.
- XeF\(_2\) has no lone pairs on the central atom. 
Therefore, B is correct.
- C. O–H $>$ C–H $>$ N–O (Bond Length):
- The O–H bond is the shortest, followed by the C–H bond, and the N–O bond is the longest due to the different sizes of the atoms and the bond strengths. 
Therefore, C is correct.
- D. N\(_2\) $>$ O\(_2\) $>$ H\(_2\) (Bond Enthalpy):
- Nitrogen (N\(_2\)) has the highest bond enthalpy due to the strong triple bond between nitrogen atoms.
- Oxygen (O\(_2\)) has a lower bond enthalpy than nitrogen due to the presence of a double bond.
- Hydrogen (H\(_2\)) has the lowest bond enthalpy due to the single bond between hydrogen atoms. 
Therefore, D is incorrect because bond enthalpy decreases as we move from N\(_2\) to H\(_2\).

Thus, the correct answer is (3) B, C only.