Which of the following substances can be used directly as fertilizer ? — s Block Elements Chemistry Question

💡 Solution & Explanation

Step 1: The thermal stability of alkali metal carbonates depends on the size and polarizing power of the alkali metal cation. Step 2: Smaller cations (like Na+) have higher charge density and polarize the large, unstable carbonate anion (CO3^2-) to decompose into a metal oxide and carbon dioxide. Larger cations have lower polarizing power and stabilize the carbonate lattice. Step 3: Since Caesium (Cs+) is the largest cation among the options, Cs2CO3 experiences the least polarization and has the highest thermal stability. Thus, option (a) is correct.