Consider the following

Assertion (A) Dipole moment of $\mathrm{NF}_3$ is lesser than $\mathrm{NH}_3$.

Reason (R) In $\mathrm{NF}_3$, the orbital dipole due to lone pair of electrons is in the opposite direction to the resultant dipole moment of the three $\mathrm{N}-\mathrm{F}$ bonds.

The correct answer is

Consider the following changes I and II

$$ \mathrm{O}_2^{-} \underset{\text { II }}{\longleftarrow} \mathrm{O}_2 \xrightarrow[\text { I }]{ } \mathrm{O}_2^{+} $$

The correct statements about these changes (I) and (II) in accordance with MO theory are

(A) In (I) bond order increases by 0.5 from the existing value

(B) In (II) bond order decreases by 1.0 from the existing value

(C) In both (I) and (II) magnetic property is not changed

(D) In both (I) and (II) magnetic property is changed

The increasing order of number of lone pair of electrons on the central atom of the following molecules is

(I) $\mathrm{ClF}_3$

(II) $\mathrm{XeF}_2$

(III) $\mathrm{SF}_4$

(IV) $\mathrm{SiH}_4$

Identify the correct set of molecules with zero dipole moment