i. When calcium oxide (slaked lime) is mixed with water, calcium hydroxide is formed with evolution of large amount of heat.
ii. When sugar is heated, it decomposes to form carbon (black substance).
iii. When an electric current is passed through acidulated water, it decomposes into hydrogen and oxygen gas.
iv. When zinc powder is added to copper sulphate solution, more reactive zinc displaces less reactive copper from copper sulphate solution. The colourless zinc sulphate is formed with evolution of heat.
v. When iron powder is added to copper sulphate solution, more reactive iron displaces less reactive copper from copper sulphate. The colourless ferrous sulphate solution is formed with evolution of heat.
