The bond energy of B-F bond in ${\mathrm{BF}}_3$ is 646 kJ ${\mathrm{mol}}^{-1}$, while that of N-F bond in ${\mathrm{NF}}_3$ is 280 kJ ${\mathrm{mol}}^{-1}$. This is because

1.  N is more electronegative than B

2.  The atomic mass of N is higher than that of B

3.  The B-F bond gets a partial double bond character due to p-p overlap

4.  N has a lone pair of electrons while B does not have

 

 

The product formed by the reaction of  diborane and ammonia in the presence of heat is:

1.  ${\mathrm{BH}}_3$

2.  ${\mathrm{NH}}_4{\mathrm{BH}}_4$

3.  ${\mathrm{NH}}_2{\mathrm{NH}}_2$

4.  ${\mathrm{B}}_3{\mathrm{N}}_3{\mathrm{H}}_6$

What is the correct order of Lewis acid strength for the following compounds:\(B B r_3, B C l_3 \text {, and } B F_3\)?

1.  ${\mathrm{BBr}}_3$ < ${\mathrm{BCl}}_3$ < ${\mathrm{BF}}_3$

2.  ${\mathrm{BCl}}_3$ < ${\mathrm{BF}}_3$ < ${\mathrm{BBr}}_3$

3.  ${\mathrm{BF}}_3$ < ${\mathrm{BCl}}_3$ < ${\mathrm{BBr}}_3$

4.  ${\mathrm{BBr}}_3$ < ${\mathrm{BF}}_3$ < ${\mathrm{BCl}}_3$

The element that combines with oxygen to give an amphoteric oxide is

1.  N

2.  P

3.  Al

4.  Na

Hydrolysis of ${\mathrm{BCl}}_3$ gives X which on treatment with sodium carbonate produces Y. X and Y, respectively, are 

1.  ${\mathrm{H}}_2{\mathrm{BO}}_3<mspace\; width="1em"></mspace>\mathrm{and}<mspace\; width="1em"></mspace>{\mathrm{NaBO}}_2$

2.  ${\mathrm{H}}_3{\mathrm{BO}}_3<mspace\; width="1em"></mspace>\mathrm{and}<mspace\; width="1em"></mspace>{\mathrm{Na}}_2{B}_4{O}_7$

3.  ${\mathrm{B}}_2{\mathrm{O}}_3<mspace\; width="1em"></mspace>\mathrm{and}<mspace\; width="1em"></mspace>{\mathrm{NaBO}}_2$

4.  $B_2{O}_3<mspace\; width="1em"></mspace>\mathrm{and}<mspace\; width="1em"></mspace>{\mathrm{Na}}_2{B}_4{O}_7$

In the structure of borax, the numbers of boron atoms and B-O-B units, respectively, are

1.  4 and 5

2.  4 and 3

3.  5 and 4

4.  5 and 3

All the products formed in the oxidation of ${\mathrm{NaBH}}_4<mspace\; width="1em"></mspace>\mathrm{and}<mspace\; width="1em"></mspace>{\mathrm{l}}_2$, are

1.  ${\mathrm{B}}_2{\mathrm{H}}_6<mspace\; width="1em"></mspace>\mathrm{and}<mspace\; width="1em"></mspace>\mathrm{Nal}<mspace\; width="1em"></mspace>\mathrm{only}$

2.  ${\mathrm{B}}_2{\mathrm{H}}_6,<mspace\; width="1em"></mspace>{\mathrm{H}}_2<mspace\; width="1em"></mspace>\mathrm{and}<mspace\; width="1em"></mspace>\mathrm{Nal}<mspace\; width="1em"></mspace>$

3.  ${\mathrm{Bl}}_3<mspace\; width="1em"></mspace>\mathrm{and}<mspace\; width="1em"></mspace>\mathrm{NaH}$

4.  ${\mathrm{NaBl}}_4<mspace\; width="1em"></mspace>\mathrm{and}<mspace\; width="1em"></mspace>\mathrm{Hl}<mspace\; width="1em"></mspace>$

${\mathrm{Al}}_2{\mathrm{O}}_3$ reacts with 

1.  Only water

2.  Only acids

3.  Only alkalis

4.  Both acids and alkalis

The major products obtained in the reaction of oxalic acid with conc. ${\mathrm{H}}_2{\mathrm{SO}}_4$ upon heating are

1.  $\mathrm{CO},<mspace\; width="1em"></mspace>{\mathrm{CO}}_2,<mspace\; width="1em"></mspace>{\mathrm{H}}_2\mathrm{O}$

2.  $\mathrm{CO},<mspace\; width="1em"></mspace>{\mathrm{SO}}_2,<mspace\; width="1em"></mspace>{\mathrm{H}}_2\mathrm{O}$

3.  ${\mathrm{H}}_2\mathrm{S},<mspace\; width="1em"></mspace>\mathrm{CO},<mspace\; width="1em"></mspace>{\mathrm{H}}_2\mathrm{O}$

4.  $\mathrm{HCOOH},<mspace\; width="1em"></mspace>{\mathrm{H}}_2\mathrm{S},<mspace\; width="1em"></mspace>\mathrm{CO}$

${\mathrm{Na}}_2{\mathrm{B}}_4{\mathrm{O}}_7\cdot 10{\mathrm{H}}_2\mathrm{O}<mspace\; width="1em"></mspace>\underset{∆}{\overset{{740}^{\circ }\mathrm{C}}{\to }}<mspace\; width="1em"></mspace>2{\mathrm{NaBO}}_2+\left(\mathrm{X}\right)+10{\mathrm{H}}_2\mathrm{O}$
$\left(\mathrm{X}\right)+{\mathrm{CaF}}_2+{\mathrm{H}}_2{\mathrm{SO}}_4⟶\mathrm{Y}+{\mathrm{CaSO}}_4+{\mathrm{H}}_2\mathrm{O}$
$\left(\mathrm{Y}\right)+{\mathrm{NaBH}}_4⟶\left(\mathrm{Z}\right)+{\mathrm{NaBF}}_4$

Select the incorrect statement regarding compounds (X), (Y) and (Z).

1.  Compound (X) is ${\mathrm{B}}_2{\mathrm{O}}_3$ and compound (Z) contains two 3C - 2e bonds

2.  Compound (X) is ${\mathrm{B}}_2{\mathrm{O}}_3$ and compound (Y) contains one 3C - 2e bonds 

3.  Compound (Y) is Lewis acid and stable due to $p\pi -p\pi$ back bonding

4.  Compound (Z) reacts with excess of ${\mathrm{NH}}_3$ at high temperature gives inorganic graphite