Semiconductors

Q.

Why Nitrogen has maximum covalency of $4$?

Q.

A p-type semiconductor is

1. Positively charged

2. Negatively charged

3. Uncharged

4. Neutral

Q.

Why BF₃ is a stable compound even if boron is not satisfying the octet rule?

Q.

Silicon doped with electron-rich impurity forms .................

(a) P-type semiconductor (b) n-type semiconductor

(c) intrinsic semiconductor (d) insulator

Q.

How does the doping increase the conductivity of semiconductors?

Q.

What is semiconductor ? Describe the two main types of semiconductors and contrast their conduction mechanism.

Q.

Reason for doping of impurities in semiconductors is to

1. Increase the conductivity of semiconductor

2. to increase magnetic properties

3. none of these

4. Increase the hardness of semiconductor

Q.

The intrinsic semiconductor behaves as insulator at?

1. $0\mathrm{K}$

2. $0°\mathrm{C}$

3. $100\mathrm{K}$

4. $100°\mathrm{C}$

Q. The ratio of a specific charge of an electron to that of proton is?

Q.

Which of the following will produce p-type semiconductor?

1. Gallium doped with Arsenic

2. Germanium doped with gallium

3. Silicon doped with phosphorus

4. Germanium doped with Arsenic

Q.

With which one of the following elements silicon should be doped so as to give p-type of semiconductor?

1. Selenium

2. Boron

3. Germanium

4. Arsenic

Q.

In the Lewis dot structure of Al3+ , we should draw 8 dots or to write Al only without any dot ?

Q.

Which of the following is true about the charge acquired by P-type semiconductors ?

(a) Positive (b) Neutral

(c) Negative (d) Depends on concentration of p impurity

Q.

Silicon doped with electron rich impurity forms:

1. p-type semiconductor

2. n-type semiconductor

3. Intrinsic semiconductor

4. Insulator

Q.

Which of the following statements are true about semiconductors ?

(a) Silicon doped with electron rich impurity is a p-type semiconductor

(b) Silicon doped with an electron rich impurity is an n-type semiconductor

(c) Delocalised electrons increase the conductivity of doped silicon

(d) An electron vacancy increases the conductivity of n-type semiconductor

Q.

A perfect crystal of silicon (fig) is doped with some elements as given in the options. Which of these options shows n-type semiconductors ?

Q.

Explain the bonding in coordination compounds in terms of Werner’s postulates.

Q. What is a semiconductor? Describe the two main types of semiconductors and contrast their conduction mechanism

Q.

To get a n-type semiconductor from silicon, it should be doped with a substance with valency ...................

(a) 2 (b) 1 (c) 3 (d) 5

Q. Draw the Lewis dot structures of H2SO4 and HNO3 and hence show the formal charge on each of the atoms in both cases.

Q.

Explaing why does conductivity of germanimum crystals increase on doping with galium ?

Q.

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

$\begin{array}{cc}ColumnI& ColumnII\\ A.Mginsolidstate& 1.P-typesemiconductor\\ B.MgC{l}_{2}inmoltenstate& 2.n-typesemiconductor\\ C.Siliconwithphosphorus& 3.Electrolyticconductor\\ D.Germaniumwithboron& 4.Electronicconductors\end{array}$

Q.

Under the influence of electric field, which of the following statement is true about the movement of electrons and holes in a p-type semiconductor ?

(a) Electron will move towards the positively charged plate through electron holes

(b) Holes will appear to be moving towards the negatively charge plate

(c) Both electrons and holes appear to move towards the positively charged plate

(d) Movement of electrons is not related to the movement of holes

Q.

Which of the following are true for n type semiconductor?

1. There are doped with 15^th group elements (Arsenic & Phosphorous)

2. They are doped with 13^th group elements(Boron and Aluminium

3. They have holes which helps in conduct electricity.

4. They have free e^- which helps in conduct electricity.

Q. Hybridization state of the central atom in HgCl2 is ?

Q. 67. Can gold be electroplated on silver?How?But silver is more reactive than gold.

Q.

With which one of the following elements silicon should be doped so as to give p-type of semiconductor?

1. Boron

2. Selenium

3. Germanium

4. Arsenic

Q.

Germanium or silicon becomes extrinsic semi-conductor due to

1. schottky defect

2. chemicals

3. Frenkel defect

4. Both (a) and (b)

Q. Doping of silicon (Si) with Arsenic (As) leads to

1. p-type semiconductor
2. Insulator
3. n-type semiconductor
4. Metal

Q.

Which one of the following can be made n-type semiconductor only when doped with some group 15 elements like P or As?

1. Cl

2. Si

3. Ne

4. Mg