QUES 5: (a) name two metal which will not liberate hydrogen from tetraoxosulphate(iv) acid (b) what is the function of calcium fluoride in the extraction of calcium by the electrolysis of fused calcium chloride (c) write short note on the following: (i) cement (ii) limestone (iii) slake lime

Here are the answers to QUES 5:

a) The metals that will not liberate hydrogen from dilute tetraoxosulphate(IV) acid (sulfuric acid) are those that are less reactive than hydrogen in the reactivity series.

• Two such metals are copper and silver.

b) The function of calcium fluoride ($\text{CaF}_2$) in the extraction of calcium by the electrolysis of fused calcium chloride ($\text{CaCl}_2$) is to lower the melting point of the calcium chloride. This reduces the energy required for the electrolysis process.

c) Short notes on the following: * (i) Cement: A fine powder, typically made from limestone and clay, that acts as a binding agent. When mixed with water, it forms a paste that hardens and adheres to other materials, making it a crucial component in concrete and mortar for construction. * (ii) Limestone: A common sedimentary rock composed primarily of calcium carbonate ($\text{CaCO}_3$). It is widely used as a building material, an aggregate for concrete, and a raw material in the production of cement and lime. * (iii) Slake lime (Slaked lime): The common name for calcium hydroxide ($\text{Ca(OH)}_2$). It is produced by adding water to quicklime (calcium oxide, $\text{CaO}$) in a process called slaking. It is used in agriculture to neutralize acidic soils, in water treatment, and in various industrial processes.