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

${\mathrm{Al}}_2{\mathrm{O}}_3$ formation involves large quantity of heat evolution which makes its use in:

1.  deoxidizer

2.  confectionary

3.  indoor photography

4.  thermite welding

Al and Ga have the same covalent radii because of:

1. Greater shielding power of s-electrons of Ga atoms

2. Poor shielding power of s-electrons of Ga atoms

3. Poor shielding power of d-electrons of Ga atoms

4. Greater shielding power of d-electrons of Ga atoms

Which is used as mordant?

1.  ${\mathrm{AlCl}}_3$

2.  ${\mathrm{Al}}_2{\left({\mathrm{SO}}_4\right)}_3$

3.  $\mathrm{Alum}$

4.  ${\mathrm{Al}}_2{\mathrm{O}}_3$

Hybridisation of boron in diborane is:

1.  $\mathrm{sp}$

2.  ${\mathrm{sp}}^2$

3.  ${\mathrm{sp}}^3$

4.  ${\mathrm{sp}}^3{\mathrm{d}}^2$

The blue coloured mineral 'Lapis Lazuli' used as semi precious stone is:

1.  sodium alumino silicate

2.  zinc cobaltate

3.  prussian blue

4.  basic copper carbonate

Red liquor is:

1.  ${\left({\mathrm{CH}}_3\mathrm{COO}\right)}_3 \mathrm{Al}$

2.  $\mathrm{Al}{\left(\mathrm{OH}\right)}_3$

3.  ${\mathrm{Al}}_2{\left({\mathrm{CO}}_3\right)}_3$

4.  ${\mathrm{Al}}_2{\left({\mathrm{SO}}_4\right)}_3$

Boron carbide, ${\mathrm{B}}_4\mathrm{C}$ is widely used for:

1.  making acetylene

2.  making plaster of Paris

3.  as a hardest substance after diamond

4.  making boric acid

Which one is explosive?

1.  ${\mathrm{PCl}}_5$

2.  $\mathrm{Pb}{\left({\mathrm{NO}}_3\right)}_2$

3.  ${\mathrm{NH}}_4{\mathrm{NO}}_3 + \mathrm{Al} \mathrm{powder}$

4.  ${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{NO}}_2$