అగ్నిమాపక యంత్రాలలో ఏ వాయువును ఉపయోగిస్తారు? General science...

1. Which gas is known as 'laughing gas'?
   (A) CO
   (B) CO₂
   (C) NO
   (D) CH₄
   Answer: Nitrous oxide (N₂O)

2. What is the chemical formula of water?
   (A) H₂O
   (B) CO₂
   (C) O₂
   (D) H₂SO₄
   Answer: (A) H₂O

3. Acid turns blue litmus to:
   (A) Blue
   (B) Red
   (C) Green
   (D) Yellow
   Answer: (B) Red

4. Which gas is used in fire extinguishers?
   (A) Oxygen
   (B) Nitrogen
   (C) Helium
   (D) Carbon dioxide
   Answer: (D) Carbon dioxide

5. Rusting of iron is a:
   (A) Chemical change
   (B) Physical change
   (C) Both
   (D) None
   Answer: (A) Chemical change

6. The most reactive metal is:
   (A) Gold
   (B) Copper
   (C) Potassium
   (D) Zinc
   Answer: (C) Potassium

7. Which of the following is not a noble gas?
   (A) Neon
   (B) Hydrogen
   (C) Argon
   (D) Helium
   Answer: (B) Hydrogen

8. Atomic number of carbon is:
   (A) 12
   (B) 8
   (C) 6
   (D) 10
   Answer: (C) 6

9. The common salt used in food is:
   (A) Sodium chloride
   (B) Potassium nitrate
   (C) Calcium carbonate
   (D) Sodium carbonate
   Answer: (A) Sodium chloride

10. What is the pH of pure water?
    (A) 5
    (B) 6
    (C) 7
    (D) 8
    Answer: (C) 7