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Carbon, silicon and germanium have four valence electrons each. At room temperature which one of the following statements is most appropriate ?

  • Option 1)

    The number of free electrons for conduction is significant only in Si and Ge but small in C.

  • Option 2)

    The number of free conduction electrons is significant in C but small in Si and Ge.

  • Option 3)

    The number of free conduction electrons is negligibly small in all the three.

  • Option 4)

    The number of free electrons for conduction is significant in all the three.

 

Answers (1)

As we learnt in

Insulator -

When energy gap is more than 3 e.v.

- wherein

1) Electrical conductivity is negligible     

2)\Delta E_{g} > 3\: ev

3) Free electrons density is negligible

 

 

Semiconductor -

Energy gap between valence band and conduction band is less than 3 e.v.

- wherein

1) \Delta E_^{g} lies between conductor & insulator 

2) Both electron and holes are responsible for conductivity .

3)    At 0 K behave like an insulator (Si,Ge)

 

 Since carbon is non-metal while silicon and germanium are semiconductor hence at room temperature free electron for conduction is significant for Si and Ge but negligible in carbon. 

Correct option is 1.

 

 


Option 1)

The number of free electrons for conduction is significant only in Si and Ge but small in C.

This is the correct option.

Option 2)

The number of free conduction electrons is significant in C but small in Si and Ge.

This is an incorrect option.

Option 3)

The number of free conduction electrons is negligibly small in all the three.

This is an incorrect option.

Option 4)

The number of free electrons for conduction is significant in all the three.

This is an incorrect option.

Posted by

Sabhrant Ambastha

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