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Q1-4 Select the correct gas. Which of the following gases ...
Q5-9: Several tests for gases are:
Select the correct test for the gas which is produced ...
10. An unknown compound was added to acid and produced a gas which turned limewater milky. The compound could be ...
Question 1:
Relights a glowing splint → Oxygen (O₂)
*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret. Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.
Question 2:
Turns limewater milky → Carbon dioxide (CO₂)
Question 3:
Bleaches damp blue litmus paper white → Chlorine (Cl₂)
Question 4:
Ignites with a pop when a burning splint is applied → Hydrogen (H₂)
Question 5:
During the complete combustion of a fuel → Product: Carbon dioxide
→ Test: A. turn limewater milky
Question 6:
When zinc reacts with hydrochloric acid → Product: Hydrogen
→ Test: C. gives a squeaky pop with a lit splint
Question 7:
During the catalytic decomposition of hydrogen peroxide → Product: Oxygen
→ Test: B. relights a glowing splint
Question 8:
When sodium metal reacts with water → Product: Hydrogen
Question 9:
During the electrolysis of molten zinc chloride → Zinc chloride (ZnCl₂) electrolysis produces zinc at cathode, chlorine at anode → Chlorine gas
→ Test: D. bleaches damp universal indicator paper
Question 10:
The gas that turns limewater milky is carbon dioxide (CO₂).
To produce CO₂ from an acid, the unknown compound must contain carbonate (CO₃²⁻) ions. Acid + carbonate → salt + water + CO₂.
From the options:
A. Sodium chloride (NaCl) — no carbonate → no CO₂
B. Potassium sulfate (K₂SO₄) — no carbonate → no CO₂
C. Magnesium nitrate (Mg(NO₃)₂) — no carbonate → no CO₂
D. Calcium carbonate (CaCO₃) — carbonate, reacts with acid → CO₂ → limewater milky
Correct answer: D