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.

Explanation

To solve the question regarding n-type silicon and determine which statement is true, we can analyze each option step by step.

### Step 1: Understand n-type Silicon
- n-type silicon is formed by doping pure silicon (Si) with pentavalent atoms (elements with five valence electrons). Common dopants include phosphorus (P), arsenic (As), and antimony (Sb).
- In n-type semiconductors, the majority charge carriers are electrons, while holes (the absence of electrons) are the minority charge carriers.

### Step 2: Analyze Each Statement
- **(a)** Electrons are majority carriers and trivalent atoms are the dopants.
- This statement is incorrect because trivalent atoms (like boron) are used to create p-type semiconductors, not n-type.

- **(b)** Electrons are majority carriers and pentavalent atoms are the dopants.
- This statement is correct. In n-type silicon, electrons are indeed the majority carriers, and pentavalent atoms (like phosphorus) are used as dopants.

- **(c)** Holes are minority carriers and pentavalent atoms are the dopants.
- This statement is partially correct in that holes are minority carriers, but it incorrectly states that pentavalent atoms are the dopants without mentioning that they create electrons as majority carriers.

- **(d)** Holes are minority carriers and trivalent atoms are the dopants.
- This statement is incorrect for the same reason as (a); trivalent atoms are not used in n-type semiconductors.

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