Assign oxidation number to the underlined elements in each of the following species :
`Naul(B)H_(4)`

Explanation

To find the oxidation number of boron in the compound NaBH₄, we can follow these steps:

### Step 1: Identify the oxidation states of known elements.
- Sodium (Na) typically has an oxidation state of +1.
- Hydrogen (H) in this case is present as a hydride ion (H⁻), which has an oxidation state of -1.

### Step 2: Write the equation for the overall charge.
Since NaBH₄ is a neutral compound, the sum of the oxidation states must equal zero. We can express this mathematically as follows:
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