${\mathrm{BCl}}_3$ 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.  ${\mathrm{CHCl}}_3$

Butter of tin is:

1.  ${\mathrm{SnCl}}_2·5{\mathrm{H}}_2\mathrm{O}$

2.  ${\mathrm{SnCl}}_4·5{\mathrm{H}}_2\mathrm{O}$

3.  ${\mathrm{SnBr}}_2·2{\mathrm{H}}_2\mathrm{O}$

4.  ${\mathrm{SnBr}}_4·5{\mathrm{H}}_2\mathrm{O}$

Ordinary glass is:

1. Sodium silicate

2. Copper silicate

3. Calcium silicate

4. A mixture of calcium and sodium silicates with silica

The substance used to impart green colour to glass is:

1.  ${\mathrm{Cu}}_2\mathrm{O}$

2.  $\mathrm{CdS}$

3.  ${\mathrm{MnO}}_2$

4.  ${\mathrm{Cr}}_2{\mathrm{O}}_3$

Carbogen is:

1.  A mixture of ${\mathrm{O}}_2+5-10\% of {\mathrm{CO}}_2$.

2.  Used by pneumonia patients for respiration.

3.  Used by victims of $\mathrm{CO}$ for respiration.

4.  All of the above.

Death due to gunshot is caused by poisoning of:

1.  Hg

2.  Pb

3.  Fe

4.  As