Question

Consider the following statements and arrange in the order of true/false as given in the codes.
$S_1:$ The hydrogen bond in salt, $KH{F}_2$ is stronger than that in gaseous $HF$.
$S_2:$ The dipole moment of $C{H}_{3}F$ is greater than that of $C{H}_{3}Cl$.
$S_3:$ $s{p}^2$ hybrid orbitals have equal $s$ and $p$ character.
$S_4:$ Two types of bond present in $B_2{H}_6$ are covalent and three center-two electrons bonds.

• A. $TTFF$
• B. $TFFT$
• C. $FFFT$
• D. $FFTT$

Answer 1

Answer: (B)

$TFFT$

$S_1:KH{F}_2,F-H-F;\Delta H\approx -212kJmo{l}^{-1}$, involves resonance H - F - H $\leftrightarrow$ H - F - H.
HF, F - H - F; $\Delta H\approx -28.6kJmo{l}^{-1}$

$S_2:C{H}_{3}Cl>C{H}_{3}F$ due to large charge separation in CH${}_3$Cl as compared to that in CH${}_3$F.
$C{H}_{3}F;\mu =1.85D,C{H}_{3}Cl;\mu =1.87D$

$S_3;$ In sp${}^2$ hybrid orbital s character is 33.3% and p character is 66.6%
Terminal $B-H$ bond is covalent while bridging $B-H$ bonds are three centre - two electron bonds.