Ans: CaO (Calcium oxide)
Q32. What is bleaching powder? Give its formula.
Ans: Bleaching powder is Ca(OCl)2, used for disinfecting and bleaching.
Q33. Why is double displacement reaction also called precipitation reaction?
Ans: Because it often forms an insoluble product called precipitate.
Q34. Give an example of a double displacement reaction.
Ans: Na2SO4 + BaCl2 → BaSO4 (↓) + 2NaCl
Q35. What is the color of ferrous sulphate?
Ans: Green
Q36. What is observed when iron nail is dipped in copper sulphate?
Ans: The solution turns green and a brown coating of copper forms on iron.
Q37. Define combination reaction.
Ans: A reaction where two or more reactants combine to form one product.
Q38. Which gas is evolved during reaction of baking soda with vinegar?
Ans: Carbon dioxide (CO2)
Q39. What type of reaction is used in fire extinguishers?
Ans: Acid-base neutralization reaction