The compound which contains both ionic and covalent bonds is

Options

A. `NH_(4)Cl`
B. `CsBr_(3)`
C. `KCN`
D. `SiO_(2)`

Explanation

To determine which compound contains both ionic and covalent bonds, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Identify the Compounds**:
The compounds we need to analyze are:
- NH4Cl (Ammonium chloride)
- CsBr3 (Cesium tribromide)
- KCN (Potassium cyanide)
- SiO2 (Silicon dioxide)

2. **Analyze NH4Cl**:
- NH4Cl consists of NH4+ (ammonium ion) and Cl- (chloride ion).
- The bond between NH4+ and Cl- is ionic.
- Within NH4+, the bonds between nitrogen (N) and hydrogen (H) are covalent.
- **Conclusion**: NH4Cl contains both ionic and covalent bonds.

3. **Analyze CsBr3**:
- CsBr3 dissociates into Cs+ (cesium ion) and Br3- (tribromide ion).
- The bond between Cs+ and Br3- is ionic.
- The Br3- ion consists of covalent bonds between the bromine atoms.
- **Conclusion**: CsBr3 contains both ionic and covalent bonds.

4. **Analyze KCN**:
- KCN dissociates into K+ (potassium ion) and CN- (cyanide ion).
- The bond between K+ and CN- is ionic.
- The CN- ion consists of a triple bond between carbon (C) and nitrogen (N), which is covalent.
- **Conclusion**: KCN contains both ionic and covalent bonds.

5. **Analyze SiO2**:
- SiO2 is a covalent network solid.
- All the bonds in SiO2 are covalent bonds between silicon (Si) and oxygen (O).
- **Conclusion**: SiO2 contains only covalent bonds and no ionic bonds.

6. **Final Answer**:
The compounds that contain both ionic and covalent bonds are:
- NH4Cl
- CsBr3
- KCN