The best reducing agent is

1. ${\mathrm{GeCl}}_2$

2. ${\mathrm{SnCl}}_2$

3. ${\mathrm{PbCl}}_2$

4. ${\mathrm{PbCl}}_4$

Boric acid on heating at $150°\mathrm{C}$ gives

1.  ${\mathrm{B}}_2{\mathrm{O}}_3$

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

3.  ${\mathrm{HBO}}_2$

4.  ${\mathrm{H}}_2{\mathrm{BO}}_3$

Identify more than one correct resonance structure of carbon dioxide from the ones given below:

a.  ${}^{-}\mathrm{O}-\mathrm{C}={\mathrm{O}}^{+}$

b.  $\mathrm{O}=\mathrm{C}=\mathrm{O}$

c.  ${}^{-}\mathrm{O}\equiv \mathrm{C}-{\mathrm{O}}^{+}$

d.  ${}^{-}\mathrm{O}-\mathrm{C}\equiv {\mathrm{O}}^{+}$

Choose the correct option:

The protective film of oxide on the surface of Al metal may be strengthened by:

1. galvanizing

2. cathodizing

3. sheradizing

4. anodizing

Given below are two statements: 

The silicate anion in the mineral kinoite is a chain of three ${\mathrm{SiO}}_4$ tetrahedra, that share corners with adjacent tetrahedra. The charge of the silicate anion is-

1. -4                                 

2. -8

3. -6                                 

4. -2

Which compound is formed when iron reacts with carbon?

1. ${\mathrm{FeC}}_2$       

2. ${\mathrm{Fe}}_3{\mathrm{C}}_{}$     

3. ${\mathrm{FeC}}_3$ 

 4. ${\mathrm{Fe}}_2\mathrm{C}$