The reaction of MgO (magnesium oxide) with H2O (water) is a combination reaction. Here's why:

* Combination Reaction: A combination reaction is where two or more reactants combine to form a single product.

* The Reaction: When magnesium oxide (MgO) reacts with water (H2O), they combine to form magnesium hydroxide (Mg(OH)2):

```

MgO + H2O → Mg(OH)2

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Key Points:

* Exothermic: This reaction is exothermic, meaning it releases heat.

* Formation of a Base: Magnesium hydroxide (Mg(OH)2) is a base, so this reaction is also a neutralization reaction (acid + base → salt + water).

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