The incorrect statement among the following is -

1. ${\mathrm{PbX}}_2$ is more stable than ${\mathrm{PbX}}_4$

2. ${\mathrm{PbCl}}_4$ is less stable than ${\mathrm{SnCl}}_4$ but ${\mathrm{PbCl}}_2$ is more stable than ${\mathrm{SnCl}}_2$

3. ${\mathrm{PbCl}}_4$ is less stable than ${\mathrm{SnCl}}_4$

4. Pb(II) is a good reducing agent while Sn(II) is not

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. ${\mathrm{H}}_2{\mathrm{BO}}_3$

Orthoboric acid when heated to red hot gives-

 Which among the following is a gas?

1. $B{F}_3$

2. $BC{l}_3$

3. $BB{r}_3$

4. $B{I}_3$

When Al is added to the potassium hydroxide solution:

1. No reaction takes place 

2. Oxygen gas is evolved

3. Water is produced 

4. Hydrogen gas is evolved

CO₂ and N₂ are non-supporters of combustion. However, for putting out fires CO₂ is preferred over N₂ because CO₂:

1. Does not burn.

2. Forms non-combustible products with burning substances.

3. Is denser than nitrogen.

4. Is a more reactive gas.

Quartz is made of silicon and oxygen joined in a network arrangement that is similar to:

1. Diamond

2. Graphite

3. $O_2$

4. None of the above

When ${\mathrm{SnCl}}_2$ reacts with ${\mathrm{HgCl}}_2$, the product formed is-

1. $\mathrm{Sn}+{\mathrm{HgCl}}_4$

2. $\mathrm{Sn}+{\mathrm{Cl}}_2+{\mathrm{Hg}}_2{\mathrm{Cl}}_2$

3. ${\mathrm{SnCl}}_4 \mathrm{and} {\mathrm{Hg}}_2{\mathrm{Cl}}_2$

4. None of the above

The soldiers of the Napolean army while at the Alps during freezing winter suffered a serious problem with regards to the tin buttons of their uniforms. White Metallic tin buttons get converted to grey powder. This transformation is related to-

1. An interaction with water vapour contained in humid air

2. A change in the crystalline structure of tin

3. A change in the partial pressure of $O_2$ in the air

4. An interaction with $N_2$ of air at low temperature

The amphoteric oxide among the following is -