Science & EVS – Part 7
Q1. Acids turn blue litmus paper:
Correct Answer: B. Red
Q2. Bases turn red litmus paper:
Correct Answer: B. Blue
Q3. The pH of a neutral solution at 25°C is:
Correct Answer: B. 7
Q4. Vinegar contains which acid?
Correct Answer: A. Acetic acid
Q5. The acid present in human gastric juice is:
Correct Answer: B. Hydrochloric acid
Q6. When an acid reacts with a base, the products are:
Correct Answer: A. Salt and water
Q7. Phenolphthalein in a basic solution shows what colour?
Correct Answer: B. Pink/magenta
Q8. The chemical formula of common salt is:
Correct Answer: A. NaCl
Q9. The chemical name of baking soda is:
Correct Answer: B. Sodium bicarbonate
Q10. Slaked lime is chemically:
Correct Answer: B. Ca(OH)2
Q11. Antacids relieve indigestion by:
Correct Answer: B. Neutralising excess stomach acid
Q12. Light travels in a vacuum at approximately:
Correct Answer: B. 3 * 10^8 m/s
Q13. Light travels in a homogeneous medium in:
Correct Answer: B. Straight lines
Q14. According to the laws of reflection, the angle of incidence equals the:
Correct Answer: B. Angle of reflection
Q15. Reflection from a smooth surface like a mirror is called:
Correct Answer: B. Regular (specular) reflection
Q16. Image formed by a plane mirror is:
Correct Answer: B. Virtual, erect and same size
Q17. A convex mirror always forms an image that is:
Correct Answer: C. Virtual, erect and diminished
Q18. Concave mirrors are used in:
Correct Answer: B. Solar cookers and headlamps
Q19. Diffuse reflection occurs on:
Correct Answer: C. Rough or irregular surfaces
Q20. A real image is one that:
Correct Answer: B. Can be projected onto a screen
