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

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

1.  ${\mathrm{H}}_3{\mathrm{BO}}_3 \mathrm{and} {\mathrm{NaBO}}_2$

2.  ${\mathrm{H}}_3{\mathrm{BO}}_3 \mathrm{and} {\mathrm{Na}}_2{B}_4{O}_7$

3.  ${\mathrm{B}}_2{\mathrm{O}}_3 \mathrm{and} {\mathrm{NaBO}}_2$

4.  $B_2{O}_3 \mathrm{and} {\mathrm{Na}}_2{B}_4{O}_7$

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

1. N

2. P

3. Al

4. Na

The Lewis acid strength of ${\mathrm{BBr}}_3$, ${\mathrm{BCl}}_3$ and ${\mathrm{BF}}_3$ is the order 

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

When a mixture of diborane and ammonia is heated, the final product is

1.  ${\mathrm{BH}}_3$

2.  ${\mathrm{NH}}_4{\mathrm{BH}}_4$

3.  ${\mathrm{NH}}_2{\mathrm{NH}}_2$

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

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 products formed by the oxidation of ${\mathrm{NaBH}}_4$ $\mathrm{and}$ ${\mathrm{l}}_2$ are:

1.  ${\mathrm{B}}_2{\mathrm{H}}_6$ $\mathrm{and}$ $\mathrm{Nal}$ $\mathrm{only}$

2.  ${\mathrm{B}}_2{\mathrm{H}}_6,$ ${\mathrm{H}}_2$ $\mathrm{and}$ $\mathrm{Nal}$ $$

3.  ${\mathrm{Bl}}_3$ $\mathrm{and}$ $\mathrm{NaH}$

4.  ${\mathrm{NaBl}}_4$ $\mathrm{and}$ $\mathrm{Hl}$ $$

${\mathrm{Al}}_2{\mathrm{O}}_3$ 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.  $\mathrm{CO}, {\mathrm{CO}}_2, {\mathrm{H}}_2\mathrm{O}$

2.  $\mathrm{CO}, {\mathrm{SO}}_2, {\mathrm{H}}_2\mathrm{O}$

3.  ${\mathrm{H}}_2\mathrm{S}, \mathrm{CO}, {\mathrm{H}}_2\mathrm{O}$

4.  $\mathrm{HCOOH}, {\mathrm{H}}_2\mathrm{S}, \mathrm{CO}$

Which element does not form alum?

1.  Fe

2.  Li

3.  K

4.  Al