Mark the oxide which is amphoteric in character

(1) CO₂

(2) CO

(3) SnO₂

(4) CaO

In B₂H₆ 

(1) there is direct boron-boron bond

(2) the structure is similar to that of C₂H₆

(3) the boron atoms are linked through hydrogen bridges

(4) all the atoms are in one plane

Which of the following cation can not give borax bead test?

(a) ${\mathrm{Cr}}^{3+}$                          (b) ${\mathrm{Co}}^{2+}$

(c) ${\mathrm{Ag}}^{+}$                           (d) ${\mathrm{Mn}}^{2+}$

Aluminium becomes passive in nitric acid because it:

1.  is a noble metal

2.  forms a thin film of oxide

3.  positive reduction potential

4.  none of the above

Hybridisation of boron in diborane is:

1.  $\mathrm{sp}$

2.  ${\mathrm{sp}}^2$

3.  ${\mathrm{sp}}^3$

4.  ${\mathrm{sp}}^3{\mathrm{d}}^2$

${\mathrm{BCl}}_3$ does not exist as dimer but ${\mathrm{BH}}_3$ exist as dimer $\left({\mathrm{B}}_2{\mathrm{H}}_6\right)$ because:

1.chlorine is more electronegative than hydrogen

2.there is $\mathrm{p\pi }-\mathrm{d\pi }$ back bonding in ${\mathrm{BCl}}_3$ but ${\mathrm{BH}}_3$ does not contain such multiple bonding

3.large sized chlorine atoms do not fit in between the small boron atoms whereas small sized hydrogen atoms get fitted between boron atoms

4.none of the above

Borax bead test is responded by:

1.  divalent metals

2.  heavy metals

3.  light metals

4.  metal which forms coloured metaborates

Carbon dioxide is a gas but silica is a solid because:

1. Carbon dioxide is composed of discrete covalent ${\mathrm{CO}}_2$ molecules whereas silica has a continuous tetrahedral structure.

2. ${\mathrm{CO}}_2$ molecules are lighter than ${\mathrm{SiO}}_2$ molecules.

3. ${\mathrm{CO}}_2$ is more acidic than ${\mathrm{SiO}}_2$.

4. The melting point of silica is very high.

Which of the following shows bond in silicone?

1.  $\mathrm{Si}—\mathrm{C}—\mathrm{Si}—\mathrm{O}—\mathrm{Si}$

2.  $\mathrm{Si}—\mathrm{C}—\mathrm{Si}—\mathrm{C}—\mathrm{Si}$

3.  $—\stackrel{\mathbf{|}}{\mathrm{Si}}—\mathrm{O}—\stackrel{\mathbf{|}}{\mathrm{Si}}—\mathrm{O}—\stackrel{\mathbf{|}}{\mathrm{Si}}—$

4.  $\mathrm{Si}—\mathrm{Si}—\mathrm{Si}—\mathrm{Si}$

$\mathrm{CO}$ reacts with chlorine in presence of sunlight to give:

1.  ${\mathrm{COCl}}_2$

2.  ${\mathrm{CO}}_2$

3.  ${\mathrm{CCl}}_4$

4.  ${\mathrm{CHCl}}_3$