In an n- type silicon, which of the following statements is true ?
(a) Electrons are majority carries and trivalent atoms are the dopants.
(b) Electrons are majority carries and pentavalent atoms are the dopants.
(c ) Holes are minority carries and paentavalent atoms are the dopants.
(d) Holes are minority carries and trivalent atoms are the dopants.

Options

A. Electrons are majority carriers and trivalent atoms are the dopants
B. Electrons are minority carriers and pentavalent atoms are the dopants
C. Holes are minority carriers and pentavalent atoms are the dopants
D. Holes are majority carriers and trivalent atoms are the dopants.

Answer

To determine which statement about n-type silicon is true, we need to analyze the properties of n-type semiconductors and the role of dopants.

### Step-by-Step Solution:

1. **Understanding n-type Semiconductors**:
- An n-type semiconductor is formed when silicon (which has four valence electrons) is doped with impurities that have five valence electrons. This creates extra electrons that contribute to electrical conduction.

2. **Identifying the Dopants**:
- The dopants used for n-type semiconductors are typically pentavalent atoms. Examples of pentavalent dopants include phosphorus (P), arsenic (As), and antimony (Sb).

3. **Majority and Minority Carriers**:
- In n-type semiconductors, the majority carriers are electrons because the doping process introduces additional free electrons. Conversely, holes (which are the absence of electrons) are the minority carriers.

4. **Analyzing the Statements**:
- (a) Electrons are majority carriers and trivalent atoms are the dopants. **(False)** - Trivalent atoms (like boron) are used for p-type semiconductors.
- (b) Electrons are majority carriers and pentavalent atoms are the dopants. **(True)** - This accurately describes n-type semiconductors.
- (c) Holes are minority carriers and pentavalent atoms are the dopants. **(False)** - While holes are indeed minority carriers, the statement incorrectly identifies the dopants.
- (d) Holes are minority carriers and trivalent atoms are the dopants. **(False)** - Again, trivalent atoms are not used in n-type semiconductors.

5. **Conclusion**:
- The correct answer is (b): Electrons are majority carriers and pentavalent atoms are the dopants.

### Final Answer:
(b) Electrons are majority carriers and pentavalent atoms are the dopants.