Determine the oxidation number of the underlined elements in the following species.
`ul(Si)H_(4),ul(B)H_(3),ul(B)F_(3),ul(Br)O_(4)^(-) and Hul(P)O_(4)^(2-)`

Explanation

To determine the oxidation numbers of the underlined elements in the given species, we will follow a systematic approach for each compound.

### Step-by-Step Solution:

1. **For SiH₄ (Silicon Hydride)**:
- Let the oxidation number of silicon (Si) be \( x \).
- The oxidation number of hydrogen (H) is +1.
- The equation for the compound is:
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