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WAEC Chemistry 2025 Paper

Question : 19

Total: 50

In a chemical reaction, ΔH is positive when

Solution:

Concept:

\Delta H = H_{\text{products}} - H_{\text{reactants}}

When

\Delta H > 0

, the reaction is endothermic.

Explanation:

A positive

\Delta H

means the enthalpy change is positive.

This occurs when the total enthalpy of products is greater than that of reactants.

So,

H_{\text{products}} > H_{\text{reactants}}

Therefore,

\Delta H_{\text{products}} > \Delta H_{\text{reactants}}

Answer:

Option A:

\Delta H_{\text{products}} > \Delta H_{\text{reactants}}

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