Who developed the theory of relativity? सापेता का सांत कसनेवकसत कया था? Options: 1) Issac Newton आइज़ैक यूटन 2) Charles Darwin चासडावन 3) Marie Curie मैर यूर 4) Albert Einstein अबटआइंटन


What is the minimum distance (in metres) required to hear an echo? ितिन सुननेके िलए ूनतम दू री (मीटर म) िकतनी होनी चािहए? Options: 1) 10 2) 13 3) 17 4) 21

Correct Answer: 17The velocity of sound in dry air is approximately 343 m/s at a temperature of 25 °C. Therefore, the reflecting object must be more than 17.2m from the sound source for echo to be perceived by a person located at the source....Read more