Metal protected by a layer of its own oxide is:

(1) Al 

(2) Ag

(3) Au

(4) Cu

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

(1) Fe

(2) Sn

(3) Ag

(4) Al

Aluminium metal is corroded in coastal  places near to the sea, because protective oxide film:

(1) is removed by sea water

(2) reacts with sea water

(3) is attacked by salts present in sea water

(4) reacts with sand particles

The compound among the following that used in cosmetic surgery is:

1. Silica

2. Silicates

3. Silicones

4. Zeolites

Aluminium reacts with nitrogen to form:

1. AlN

2. $A{l}_2{N}_3$

3. $A{l}_{2}N$

4. $A{l}_4{N}_6$

B-F bond order in $B{F}_3$ is:

(1) 1

(2) 2

(3) 3

(4) 4/3

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

Borax is prepared by treating boric acid with:

(1) $NaN{O}_3$

(2) NaCl

(3) $N{a}_{2}C{O}_3$

(4) $NaHC{O}_3$

Which of the following products is formed when orthoboric acid is heated to red heat?

Which of the following is responsible for the polymeric nature of boric acid?

1. Its acidic nature

2. Presence of hydrogen bonds

3. Its monobasic nature

4. Its geometry