The pair having only molecular solids among the following is -

1. Brass and SiC

2. Ammonium phosphate (NH₄)₃PO₄

3. SiC and plastic 

4. Tetra phosphorus decaoxide (P₄O₁₀) and I₂

Niobium crystallizes in body-centred cubic structure. If the density is 8.55 g cm⁻³, the atomic radius of niobium (atomic mass 93 u) is -

1. 13.32 nm

2. 12.32 nm

3. 14.32 nm

4. 15.32 nm

(i) Ge is doped with In

(ii) Si is doped with B. 

The semiconductors formed in the above cases are :

1. (i) n-type semiconductor  (ii) p-type semiconductor .

2. (i) p-type semiconductor  (ii) n-type semiconductor .

3. p-type semiconductor in both the cases.

4. n-type semiconductor in both the cases.

Select the correct option based on statements below:

Match the type of packing given in Column I with the items given in Column II.

Codes

Match the items given in Column I with the items given in Column II.

Codes

Match the types of defects given in Column I with the statement given in Column II.

Codes

Match the defects given in Column I with the statements given in Column II.

Codes

Correct statement among the following regarding conductivity in solids is -

1.   ${\mathrm{\kappa }}_{\mathrm{metals}} \gg {\mathrm{\kappa }}_{\mathrm{insulators}} < {\mathrm{\kappa }}_{\mathrm{semiconductors}}$

2.   ${\mathrm{\kappa }}_{\mathrm{metals}} \ll {\mathrm{\kappa }}_{\mathrm{insulators}} < {\mathrm{\kappa }}_{\mathrm{semiconductors}}$

3.   ${\mathrm{\kappa }}_{\mathrm{metals}} , {\mathrm{\kappa }}_{\mathrm{semiconductors}} > {\mathrm{\kappa }}_{\mathrm{insulators}} = \mathrm{zero}$

4.  ${\mathrm{\kappa }}_{\mathrm{metals}} < {\mathrm{\kappa }}_{\mathrm{semiconductors}} > {\mathrm{\kappa }}_{\mathrm{insulators}} \ne \mathrm{zero}$

The correct order of the packing efficiency in different types of unit cells is-

1.  Fcc < Bcc < Simple cubic

2.  Fcc > Bcc > Simple cubic

3.  Fcc < Bcc > Simple cubic

4.  Bcc < Fcc > Simple cubic