Non-oxide ceramics can be

Options

A. `B_(4)C`
B. `SiC`
C. `Si_(3)N_(4)`
D. All of these

Explanation

To solve the question regarding non-oxide ceramics, we will follow these steps:

### Step 1: Understand Non-Oxide Ceramics
Non-oxide ceramics are materials that do not contain oxygen in their chemical structure. They are typically characterized by their covalent bonding, high thermal conductivity, and low thermal expansion.

**Hint:** Remember that non-oxide ceramics are primarily composed of elements other than oxygen.

### Step 2: Identify Types of Non-Oxide Ceramics
The common types of non-oxide ceramics include:
- **Carbides** (compounds of carbon with a more electropositive element)
- **Nitrides** (compounds of nitrogen with a more electropositive element)
- **Oxynitrides** (compounds that contain both oxygen and nitrogen)

**Hint:** Focus on the elements involved in the compounds to classify them correctly.

### Step 3: Analyze the Given Options
The question provides options that may include various compounds. We need to identify which of these options are classified as non-oxide ceramics:
1. B4C (Boron carbide)
2. Si (Silicon)
3. Si3N4 (Silicon nitride)
4. All of the above

**Hint:** Look for the presence of oxygen in the chemical formulas to determine if they are non-oxide ceramics.

### Step 4: Classify Each Option
- **B4C (Boron carbide)**: This is a carbide and is a non-oxide ceramic.
- **Si (Silicon)**: This is a pure element and not classified as a ceramic.
- **Si3N4 (Silicon nitride)**: This is a nitride and is a non-oxide ceramic.

**Hint:** Remember that only compounds that do not contain oxygen qualify as non-oxide ceramics.

### Step 5: Conclusion
From the analysis, we can conclude that the non-oxide ceramics among the options are B4C and Si3N4. The option that includes both of these is "All of the above," which suggests that the correct answer is option 4.

**Final Answer:** Non-oxide ceramics can be B4C, Si3N4, and thus the answer is option 4: All of the above.