Currently Empty: ₹0.00
Uncategorized
Theraml Decomposition year 8 chemistry Questions
🔥 Thermal Decomposition – 20 Practice Questions
1. Define thermal decomposition.
A reaction in which a compound breaks down into simpler substances using heat.
2. What does thermal mean?
Heat.
3. Is thermal decomposition endothermic or exothermic?
Endothermic.
4. Complete: CaCO₃ → (heat) → ______ + ______
CaO + COâ‚‚
5. Which gas turns limewater milky?
Carbon dioxide (COâ‚‚).
6. True or False: Thermal decomposition is a physical change.
False. It is a chemical change.
7. What colour change occurs when copper carbonate is heated?
Green to black.
8. Write the word equation for calcium carbonate decomposition.
Calcium carbonate → Calcium oxide + Carbon dioxide
9. Which type of substance decomposes – element or compound?
Compound.
10. Multiple Choice: Which is thermal decomposition?
A) H + O → Water
B) CaCO₃ → CaO + CO₂
C) Fe + O → Rust
B
11. Why is heat required in thermal decomposition?
To break chemical bonds.
12. What solid is formed when CuCO₃ is heated?
Copper oxide (CuO).
13. Complete: MgCO₃ → (heat) → ______ + CO₂
MgO
14. True or False: Energy is released in thermal decomposition.
False. Energy is absorbed.
15. What test confirms the presence of COâ‚‚ gas?
Limewater turns milky.
16. What happens to bonds during decomposition?
Bonds are broken.
17. Give one industrial use of thermal decomposition.
Producing calcium oxide for cement manufacture.
18. Is a new substance formed in thermal decomposition?
Yes.
19. What type of reaction is the opposite of decomposition?
Combination reaction.
20. What are the two products when CaCO₃ is heated?
Calcium oxide and carbon dioxide.