Which one of the following reactions does not result in the evolutio

Which one of the following reactions does not result in the evolution of hydrogen gas ?

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Reaction of zinc metal with dilute sulphuric acid solution

Mixing water to Plaster of Paris

Heating zinc metal with sodium hydroxide solution

Reaction of potassium metal with water

Answer is Right!

Answer is Wrong!

This question was previously asked in

UPSC NDA-1 – 2021

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Mixing water with Plaster of Paris (Calcium sulfate hemihydrate, CaSO₄·½H₂O) results in a hydration reaction where water is absorbed to form gypsum (Calcium sulfate dihydrate, CaSO₄·2H₂O). This reaction is exothermic and causes the mixture to set and harden, but it does not produce any gas, including hydrogen.

The reactions in options A, C, and D all involve the liberation of hydrogen gas:
A) Active metals like zinc react with dilute acids (Zn + H₂SO₄ → ZnSO₄ + H₂).
C) Amphoteric metals like zinc react with strong bases upon heating (Zn + 2NaOH → Na₂ZnO₂ + H₂).
D) Highly reactive metals like potassium react vigorously with water (2K + 2H₂O → 2KOH + H₂).

Plaster of Paris is commonly used in construction, casting, and medical applications (like casts for broken bones) due to its ability to quickly set after mixing with water. The setting process involves the crystallization of gypsum.

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