Which of the following products is formed when boric acid, H₃BO₃, is heated to about 150°C?

1. ${\mathrm{B}}_2{\mathrm{O}}_3$

2. ${\mathrm{H}}_2{\mathrm{B}}_4{\mathrm{O}}_7$

3. ${\mathrm{HBO}}_2$

4. ${\mathrm{H}}_2{\mathrm{BO}}_3$

The product formed in the reaction,

$BC{l}_3+H_{2}O\to$Product is:

(1) $H_{3}B{O}_3+HCl$

(2) $B_2{O}_3+HOCl$

(3) $B_2{H}_6+HCl$

(4) no reaction

The correct statement among the following about H₃BO₃ is:
1. Monobasic and weak Lewis acid

2. Monobasic and weak Bronsted acid

3. Monobasic and strong Lewis acid

4. Tribasic and weak Bronsted acid

On the addition of mineral acid to an aqueous solution of borax, the compound formed is:

1. borodihydride

2. orthoboric acid

3. metaboric acid

4. pyroboric acid

Borax is prepared by treating boric acid with:

(1) $NaN{O}_3$

(2) NaCl

(3) $N{a}_{2}C{O}_3$

(4) $NaHC{O}_3$

Why is BF₃ a weaker Lewis acid than BCl₃?

1. High electronegativity of fluorine

2. Presence of three-center–two-electron bonds

3. pπ–dπ back-bonding

4. pπ–pπ back-bonding

 Which among the following is a gas?

1. $B{F}_3$

2. $BC{l}_3$

3. $BB{r}_3$

4. $B{I}_3$

B-F bond order in $B{F}_3$ is:

(1) 1

(2) 2

(3) 3

(4) 4/3

Aluminium reacts with nitrogen to form:

1. AlN

2. $A{l}_2{N}_3$

3. $A{l}_{2}N$

4. $A{l}_4{N}_6$

Which metal is powdered, suspended in oil and used as paint?

(1) Fe

(2) Sn

(3) Ag

(4) Al