Tzu En's answer to elly's Secondary 3 E Maths Singapore question.

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Tzu En
Tzu En's answer
133 answers (Tutor Details)
1st
A: HCl
B: CaCO3
C: AgCl
D: CuCl2

G is CO2

CO2 + Ca(OH)2 > CaCO3 + H2O

For the first reaction, between CaCO3 and A, CO2 was produced, suggesting that A is an acid that reacts with carbonate.
For second reaction, A reacts with AgNO3 to produce a white ppt, likely AgCl, suggesting that anion of A is Cl-.
Thus A is HCl