A chemical reaction that involves heat or light to their surrounding is called exothermic reaction. Which one of the following is not an exothermic reaction?

C. CaCO₃(s) → CaO(s) + CO₂(g)

A. CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(g)

C. CaCO₃(s) → CaO(s) + CO₂(g)

D. 2H₂(g) + O₂(g) → 2H₂O(g)

Everyday Science · Everyday & Industrial Chemistry · page 40 of 40

Some Chemical Reactions MCQs with Answers

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391.
In a mixture of NO and CO₂ (initially containing 4 mol of NO and 0.9 mol of CO₂), a reaction occurs according to the equation: NO(g) + CO₂(g) ⇌ NO₂(g) + CO(g). At equilibrium, 0.1 mol of CO₂ is present. What is the equilibrium constant (Kc) at the temperature of this experiment?
Correct Answer: D. 0.2
One-liner
The equilibrium constant Kc for the reaction is 0.2, calculated from the equilibrium concentrations of the reactants and products.
392.
Acid base reaction is an ?
Correct Answer: C. Exothermic reaction
One-liner
An acid-base reaction is an exothermic reaction because it releases heat when an acid and a base neutralize each other.
393.
A chemical reaction that involves heat or light to their surrounding is called exothermic reaction. Which one of the following is not an exothermic reaction?
Correct Answer: C. CaCO₃(s) → CaO(s) + CO₂(g)
One-liner
The reaction CaCO₃(s) → CaO(s) + CO₂(g) is not exothermic; it is an endothermic reaction that absorbs heat during the decomposition of calcium carbonate.
394.
Which property of ice is important for aquatic life?
Correct Answer: C. Ice floats on water
One-liner
Ice floats on water because it is less dense than liquid water, and this property is crucial for aquatic life.