Q1. Which of the following is NOT a sign that a chemical reaction has taken place?
Q2. The reaction CaO(s) + H₂O(l) → Ca(OH)₂(aq) is an example of:
Q3. The balanced equation for the reaction of iron with steam is:
Q4. When ferrous sulphate crystals are heated, the colour changes from:
Q5. The decomposition of silver chloride in sunlight is an example of:
Q6. In the reaction Fe(s) + CuSO₄(aq) → FeSO₄(aq) + Cu(s), the iron nail becomes brownish because:
Q7. Na₂SO₄(aq) + BaCl₂(aq) → BaSO₄(s) + 2NaCl(aq) is an example of:
Q8. In the reaction CuO + H₂ → Cu + H₂O, the reducing agent is:
Q9. Which of the following reactions is endothermic?
Q10. Rusting of iron requires the presence of:
Q11. The state symbol '(aq)' represents:
Q12. Which of the following is a precipitation reaction?
Q13. In electrolysis of water, the ratio of hydrogen to oxygen gas collected is:
Q14. Chip packets are flushed with nitrogen gas to:
Q15. Galvanisation is a method of protecting iron from rusting by coating it with:
Q16. Which of the following is an exothermic reaction?
Q17. In the reaction 2Pb(NO₃)₂(s) → 2PbO(s) + 4NO₂(g) + O₂(g), the brown fumes observed are of:
Q18. Silver articles become black after some time due to formation of:
Q19. A chemical equation is balanced to satisfy the:
Q20. Which of the following is used in black and white photography?
