Aluminium becomes passive in nitric acid because it-

1. Is a noble metal

2. Forms a thin film of oxide

3. Has a positive reduction potential

4.  None of the above

Chemically thermite is -

1.  Fe and Al

2.  Ferric oxide and aluminium powder

3.  Barium peroxide and magnesium powder

4.  Cu and aluminium

Borax bead test is responded by:

1.  Divalent metals

2.  Heavy metals

3.  Light metals

4.  Metal which forms coloured metaborates

The incorrect statement among the following is -

1. $\mathrm{Ge}{\left(\mathrm{OH}\right)}_2$ is amphoteric

2. ${\mathrm{GeCl}}_2$ is more stable than ${\mathrm{GeCl}}_4$

3. ${\mathrm{GeO}}_2$ is weakly acidic

4. GeCl₄ + 2HCl ⇄ H₂[GeCl₆]

Silicon carbide is used as:

${\mathrm{R}}_3\mathrm{SiCl}$ on complete hydrolysis forms:

1.  ${\mathrm{R}}_3\mathrm{SiOH}$

2.  ${\mathrm{R}}_3\mathrm{Si}—\mathrm{O}—{\mathrm{SiR}}_3$

3.  ${\mathrm{R}}_3\mathrm{Si}=\mathrm{O}$

4.  None of the above.

The percentage of lead in a lead pencil is-

1.  20

2.  0

3.  80

4.  70

Tin cry refers to- 

1. Conversion of white to grey tin

2. Tin plating

3. Conversion of white tetrahedral tin to white rhombohedral tin

4. Emission of sound while bending a tin rod

The correct statement regarding polymeric silicon dioxide is -

AlF₃ is soluble in HF only in the presence of KF due to the formation of: