(a) NaCl
(b) NaHCO₃
(c) CaCO₃
(d) NH₄Cl
Answer: (b) NaHCO₃
19. What gas turns lime water milky?
(a) Hydrogen
(b) Nitrogen
(c) Carbon dioxide
(d) Oxygen
Answer: (c) Carbon dioxide
20. Which substance is used to make plaster of paris?
(a) Gypsum
(b) Copper
(c) Zinc
(d) Salt
Answer: (a) Gypsum
21. What is formula of washing soda?
(a) NaHCO₃
(b) NaOH
(c) Na₂CO₃.10H₂O
(d) Ca(OH)₂
Answer: (c) Na₂CO₃.10H₂O
22. Universal indicator is:
(a) Single dye
(b) Mix of many indicators
(c) Only red litmus
(d) Salt solution
Answer: (b) Mix of many indicators
23. What should be added to soil if it is too acidic?
(a) Vinegar
(b) Lemon juice
(c) Quick lime
(d) Sulphuric acid
Answer: (c) Quick lime
24. What kind of salt is formed from strong acid + strong base?
(a) Acidic
(b) Basic
(c) Neutral
(d) Bitter
Answer: (c) Neutral
25. Which acid is in ant sting?
(a) Citric acid
(b) Acetic acid
(c) Methanoic acid
(d) Tartaric acid
Answer: (c) Methanoic acid
26. What is added to neutralize bee sting?
(a) Vinegar
(b) Baking soda
(c) Salt
(d) Oil
Answer: (b) Baking soda
27. pH scale measures:
(a) Heat
(b) Strength of acids and bases
(c) Colour
(d) Mass
Answer: (b) Strength of acids and bases
28. Which of the following is a weak acid?
(a) HCl
(b) HNO₃
(c) CH₃COOH
(d) H₂SO₄
Answer: (c) CH₃COOH
29. Which is an alkali?
(a) Base that is insoluble in water
(b) Acid
(c) Base soluble in water
(d) Salt
Answer: (c) Base soluble in water
30. What is formed when acid reacts with base?
(a) Salt
(b) Water
(c) Salt and water
(d) Hydrogen
Answer: (c) Salt and water
31. What is formed when metal reacts with acid?
(a) Salt + CO₂
(b) Salt + water
(c) Salt + H₂ gas
(d) Water only
Answer: (c) Salt + H₂ gas
32. Which acid is found in vinegar?
(a) Citric acid
(b) Tartaric acid
(c) Acetic acid
(d) Oxalic acid
Answer: (c) Acetic acid
33. What should we always add slowly to water?
(a) Soap
(b) Salt
(c) Acid
(d) Air
Answer: (c) Acid
34. Which base is used in soda-acid fire extinguisher?
(a) Sodium hydroxide
(b) Calcium hydroxide
(c) Sodium hydrogencarbonate
(d) Potassium hydroxide
Answer: (c) Sodium hydrogencarbonate
35. What type of oxide is CO₂?
(a) Basic
(b) Neutral
(c) Acidic
(d) None
Answer: (c) Acidic
