iGCSE Chemistry 0620 Extended - 7.1 The characteristic properties of acids and bases- Exam Style Questions Paper 2- New Syllabus
▶️ Answer/Explanation
Since both acids have the same concentration and volume, they contain the same amount of acid available for reaction, so the final volume of H₂ produced is the same. Acid R produces hydrogen faster initially, indicating it has a higher concentration of \(\mathrm{H^+}\) ions in solution, meaning it is more completely dissociated — acid R is a stronger acid than acid S.
✅ Answer: (C)
✅ Answer: (C)
▶️ Answer/Explanation
Ethanoic acid reacts with sodium carbonate to produce carbon dioxide gas: \(\mathrm{2CH_3COOH + Na_2CO_3 \rightarrow 2CH_3COONa + H_2O + CO_2}\).
(A) is false — ethanoic acid reacts with magnesium to form hydrogen gas, not oxygen.
(C) is false — acids turn blue litmus red, not the reverse.
(D) is false — acids turn methyl orange red/pink, not yellow (yellow is for alkalis).
✅ Answer: (B)
(A) is false — ethanoic acid reacts with magnesium to form hydrogen gas, not oxygen.
(C) is false — acids turn blue litmus red, not the reverse.
(D) is false — acids turn methyl orange red/pink, not yellow (yellow is for alkalis).
✅ Answer: (B)
▶️ Answer/Explanation
Bases react with ammonium salts to produce ammonia gas. For example: \(\mathrm{Ca(OH)_2 + 2NH_4Cl \rightarrow CaCl_2 + 2NH_3 + 2H_2O}\).
(B) describes an acid reacting with a carbonate.
(C) is incorrect — copper does not react with bases to produce hydrogen.
(D) describes an acid — acids turn blue litmus red; bases turn red litmus blue.
✅ Answer: (A)
(B) describes an acid reacting with a carbonate.
(C) is incorrect — copper does not react with bases to produce hydrogen.
(D) describes an acid — acids turn blue litmus red; bases turn red litmus blue.
✅ Answer: (A)