Four instruments have been given, out of which three are alike in some manner and one is different. Select the one that is different from the rest:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Deciblemeter
To identify the odd one out, we must look at what each instrument measures:
- Udometer: An instrument used to measure the amount of liquid precipitation (rain) over a set period of time.
- Ombrometer: Another name for a rain gauge, used to measure rainfall.
- Pluviometer: Also a technical term for a rain gauge.
- Deciblemeter (Decibel meter): An instrument used to measure sound intensity or noise levels in decibels ($dB$).
Conclusion
Udometer, Ombrometer, and Pluviometer are all synonyms for the same device—a rain gauge. The Deciblemeter is the only instrument in the list used for measuring sound, making it the different one.