Match List I with List II and select the answer using the code given below the Lists : List I (Reaction) A. CaO (s) + H2O (1) -> Ca(OH)2 (aq) B. CaCO3 (s) -> CaO (s) + CO2 (g) C. Pb (s) + CuCl2 (aq) -> PbCl2 (aq) + Cu (s) D. Na2SO4 (aq) + BaCl2 (aq) -> BaSO4 (s) + 2NaCl (aq) List II (Type) 1. Single displacement 2. Double displacement 3. Combination 4. Decomposition Code : ABCD (a) 2 1 4 3 (b) 2 4 1 3 (c) 3 4 1 2 (d) 3 1 4 2

The chemical reactions are classified based on the interaction of reactants. Reaction A (CaO + H2O → Ca(OH)2) is a combination reaction because two reactants combine to form a single product [2]. Reaction B (CaCO3 → CaO + CO2) is a decomposition reaction, where a single compound breaks down into two or more simpler substances. Reaction C (Pb + CuCl2 → PbCl2 + Cu) is a single displacement reaction, as lead (Pb) replaces copper (Cu) from its salt solution [2]. Reaction D (Na2SO4 + BaCl2 → BaSO4 + 2NaCl) is a double displacement reaction, characterized by the exchange of ions between two compounds to form new products, often resulting in a precipitate like BaSO4. Matching these gives A-3, B-4, C-1, D-2, which corresponds to code (c).

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 1: Chemical Reactions and Equations > QUESTIONS > p. 7
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 1: Chemical Reactions and Equations > Figure 1.3 > p. 6