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ICSE Class 10 Chemistry Question 11 of 13

Practical Work — Question 12

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Question 12

A student was asked to perform two experiments in the laboratory based on the instructions given:

Observe the picture given below and state one observation for each of the Experiments 1 and 2 that you would notice on mixing the given solutions.

(a) Experiment 1

A student was asked to perform two experiments in the laboratory based on the instructions given: ICSE 2025 Chemistry Solved Question Paper.

(b) Experiment 2

A student was asked to perform two experiments in the laboratory based on the instructions given: ICSE 2025 Chemistry Solved Question Paper.
Answer

(a) White precipitate of barium sulphate is formed.
Reason — When a solution of zinc sulphate is added to a solution of barium chloride, a double displacement reaction occurs. This reaction involves the exchange of ions between the two compounds and a white precipitate of barium sulphate is formed.
ZnSO4 (aq) + BaCl2 (aq) ⟶ BaSO4 (s) + ZnCl2 (aq).

(b) Blue precipitate dissolves to form an inky blue/deep blue solution.
Reason — The light blue precipitate of copper(II) hydroxide (Cu(OH)2) dissolves in excess of ammonium hydroxide due to the formation of a deep blue complex, tetraamminecopper(II) ([Cu(NH3)4]2+), making it soluble.