Question

2. In which of the following reactions, the colour changes from green lo black?
(A) Cuco → CuO + CO
(B) Znco. → ZnO + CO.
(©) Caco CaO + CO2
(D) 2HgO + 2Hg + O​

Answer 1

Answer:

opt a.( plz correct it... it will be Cuco3 not Cuco)

Explanation:

Copper carbonate is green and copper oxide is black. Hence colour change from green to black is seen during the reaction.

thank you.

Answer 2

CORRECT QUESTION-

In which of the following reactions, does the color change from green to black?

(A) CuCO₃ → CuO + CO₂

(B) ZnCO₃. → ZnO + CO₂.

(©) CaCO₃ → CaO + CO2

(D) 2HgO → 2Hg + O₂

ANSWER-

The correct answer is option (A) CuCO₃ → CuO + CO₂

• A Change of color indicates that a chemical reaction has occurred.
• In the first option, Copper carbonate(CuCO₃) is a green crystalline solid that under thermal decomposition produces a black inorganic compound called Cupric Oxide(CuO) and produces a colorless Carbon dioxide gas(CO₂)
• Zinc Carbonate(ZnCO₃) is a white crystalline available as a solid or powder it's thermal decomposition produces Zinc oxide(ZnO) which is a white solid and gives off Carbon dioxide
• Calcium carbonate(CaCO₃) is a yellowish white amorphous solid that upon heating decomposes into Calcium hydroxide(CaO) and carbon dioxide
• In the fourth option Mercuric oxide(HgO) is red whose decomposition results in the formation of silver-colored mercury(Hg) and gives off Oxygen gas

Thus, During The Decomposition Of Cuco₃ The Color Changes From Green To Black.

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