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SSC CGL
easyQ. No. 14864

Which gas is released when zinc reacts with dilute hydrochloric acid?

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Zinc reacts with dilute hydrochloric acid to produce zinc chloride and hydrogen gas. Zinc is more reactive than hydrogen, so it displaces hydrogen ions from the acid. Zinc changes from oxidation state 0 to +2 and is oxidised, while hydrogen ions gain electrons and are reduced to hydrogen gas. The gas is colourless and burns with a characteristic pop when a small test sample is ignited under controlled laboratory conditions. Therefore, Option B, hydrogen, is correct. Concept depth: Metals above hydrogen in the reactivity series generally release hydrogen from dilute non-oxidising acids. Copper does not normally react with dilute HCl because it lies below hydrogen in the series. The coefficient 2 before HCl balances both chlorine atoms and hydrogen atoms.

AOxygen
BHydrogen
CNitrogen
DChlorine
Correct Answer: HydrogenYour Answer: B

Explanation

Correct answer: Option B - Hydrogen. Oxygen is not produced because the reactants provide no oxidising route for O₂ formation. Nitrogen is absent from the reactants. Chloride ions remain in solution with Zn²⁺ as zinc chloride rather than forming chlorine gas under these conditions. Thus, hydrogen is the only option consistent with the balanced reaction and the metal-acid reactivity rule.

Important Notes

  • Zinc displaces hydrogen because it is above hydrogen in the reactivity series.
  • Zinc is oxidised from 0 to +2; H⁺ is reduced to H₂.
  • Hydrogen is colourless and gives a pop test under controlled conditions.

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FAQ

SSC CGL Chemistry FAQs

Common questions and clear answers for this topic.

What is the balanced equation for zinc and hydrochloric acid?

Zn + 2HCl → ZnCl₂ + H₂.

Which metal property allows zinc to release hydrogen?

Zinc lies above hydrogen in the reactivity series.

What type of reaction is this?

A single-displacement redox reaction.

How is hydrogen commonly identified in a laboratory test?

A small sample burns with a pop sound under controlled conditions.

How many chemistry questions typically appear in the SSC CGL exam?

Chemistry usually contributes a handful of questions within the General Awareness section, generally covering basic concepts rather than calculation-heavy problems.

Which chemistry topics are most important for SSC CGL preparation?

Atomic structure, periodic table trends, acids-bases-salts, metals and non-metals, and carbon compounds are the areas that appear most consistently across past papers.

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Which metal is the best conductor of electricity?Which of the following is the correct IUPAC name of CH3-CH=CH-CH3?What is the overall cell reaction in a Daniell cell?