✅ Correct Answer: Air
Source: This question is taken from the Everyday Science
✅ Correct Answer: Refraction
✅ Correct Answer: Optical Centre
✅ Correct Answer: Opaque
✅ Correct Answer: transparent
✅ Correct Answer: Frequency
✅ Correct Answer: Transmission
✅ Correct Answer: Translucent
✅ Correct Answer: Principal Axis
✅ Correct Answer: Transparent