A white powder solid A forms a light green solution with water, which on treatment with potassium hexacyanoferrate(III) gives a blue precipitate. On being strongly heated, A leaves a brown residue and

Question

A white powder solid A forms a light green solution with water, which on treatment with potassium hexacyanoferrate(III) gives a blue precipitate. On being strongly heated, A leaves a brown residue and forms a mixture of two gaseous oxides, which turns a dichromate solution green and forms a white precipitate with a BaCl2 solution containing concentrated HCl. A is:

Prashant Kotian · Accepted Answer

Correct answer: C. Step 1: The thermal decomposition of alkaline earth metal carbonates follows the equation: MCO3(s) <=> MO(s) + CO2(g). The equilibrium constant K_p for this reaction is equal to the partial pressure of CO2 (P_CO2). Step 2: The thermal stability of carbonates increases down the group as the ionic size of the cation increases and polarizing power decreases, meaning BeCO3 is the least stable and decomposes most readily. Step 3: Because BeCO3 decomposes most easily at any given temperature, it has the highest equilibrium pressure of CO2 (highest K_p), corresponding to option (a).

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