Acidic solutions from chloride hydrolysis react with Na2CO3 to produce CO2

Steps:

• Identify chlorides that hydrolyze in water to form H+ ions, enabling reaction with Na2CO3 via 2H+ + CO3^2- → H2O + CO2.
• AlCl3 hydrolyzes: AlCl3 + 3H2O → Al(OH)3 + 3HCl, producing acidic solution.
• MgCl2 dissolves to Mg^2+ and Cl-, neutral salt with minimal hydrolysis.
• SiCl4 hydrolyzes: SiCl4 + 4H2O → Si(OH)4 + 4HCl, producing acidic solution.
• PCl5 hydrolyzes: PCl5 + 4H2O → H3PO4 + 5HCl, producing acidic solution.

Why C is correct:

• Option C selects 1, 3, and 4, whose hydrolysis yields H+ ions that acidify the solution and react with carbonate per the acid-base reaction formula.

Why the others are wrong:

• A omits acidic 3 and 4 while including neutral 2.
• B omits acidic 1 while including neutral 2.
• D includes neutral 2, which forms no CO2.

Final answer: C