The speed of sound in dry air at 20C is about?

A. 343 m/s
B. 230 m/s
C. 130 m/s
D. 430 m/s

Answer

Correct Answer: A. 343 m/s

Detail about MCQs

The speed of sound in dry air at 20°C is approximately 343 meters per second (m/s). This value is affected by factors such as temperature, pressure, and humidity. In dry air at standard conditions, sound travels at this speed, which is commonly used as a reference value in physics and engineering calculations involving sound propagation

When sound is reflected from floor, ceiling or a wall, it mixes with the original sound and changes its complexion, it is called as?

A. Noise
B. Sound
C. Echo
D. None of these

Answer

Correct Answer: C. Echo

Detail about MCQs

The correct answer is C. Echo. When sound waves reflect off surfaces such as floors, ceilings, or walls and return to the listener’s ears after a brief delay, it creates an audible repetition of the original sound, known as an echo. Echoes occur due to the reflection of sound waves off solid surfaces, and they can alter the perception and quality of the original sound.

Rectified Spirit is:

A. 100% Ethyl alcohol
B. 95% Ethyl alcohol
C. Tincture iodine
D. Methylated spirit

Answer

Correct Answer: B. 95% Ethyl alcohol


Detail About MCQs

Rectified spirit contains 95% ethanol with 5% water. A rectified alcohol is highly concentrated ethanol that has been purified by means of repeated distillation, a process that is called rectification. It typically contains 95% alcohol by volume and 5 % water. Normally, ethanol with 5 % water is known as pure alcohol. 

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