Boron fluoride exists as `BF_(3)` but boron hydride does't exist as `BH_(3)`. Give reason. In which form does it exist ? Explain its structure.

Explanation

### Step-by-Step Solution

1. **Understanding the Compounds**:
- Boron fluoride (BF₃) and boron hydride (BH₃) both involve boron bonded to three atoms (fluorine and hydrogen, respectively).
- In both cases, boron has only six electrons in its outer shell, which means it does not achieve a complete octet.

2. **Existence of BF₃**:
- BF₃ exists because of the phenomenon known as back bonding.
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