Which of the following statements is incorrect, when calcium oxide reacts with water?

Correct option is C

 
The reaction of calcium oxide (CaO) with water (H₂O) is not a decomposition reaction; it is a combination reaction because two reactants (CaO and H₂O) combine to form a single product, slaked lime Ca(OH)₂.
Explanation:
· CaO + H₂O → Ca(OH)₂ + Heat
· (a) Correct: The reaction produces slaked lime (Ca(OH)₂).
· (b) Correct: The reaction is highly exothermic, releasing a large amount of heat.
· (c) Incorrect: A decomposition reaction involves breaking down a compound into two or more products. Here, compounds combine instead of breaking apart.
· (d) Correct: The balanced chemical equation has '1' as the coefficient for CaO, H₂O, and Ca(OH)₂: CaO (1) + H₂O (1) → Ca(OH)₂ (1).
Information Booster:
1. Calcium oxide (quicklime) reacts vigorously with water, forming slaked lime (Ca(OH)₂).
2. This reaction is exothermic, causing the mixture to heat up significantly.
3. Slaked lime is used in whitewashing walls because it reacts with CO₂ to form a durable CaCO₃ layer.
4. Decomposition reactions involve breaking a compound, whereas combination reactions involve joining two or more substances.
Additional Knowledge:
· Combination Reaction: Two or more reactants form a single product (e.g., CaO + H₂O → Ca(OH)₂).
· Decomposition Reaction: A single compound breaks down into simpler substances (e.g., CaCO₃ → CaO + CO₂).
· Exothermic Reactions: Reactions that release heat, such as combustion and neutralization.
· Balanced Chemical Equations: The number of atoms of each element is equal on both sides of the equation.