Answer:
Human ears can hear sound waves that vibrate in the range from about 20 times a second (a deep rumbling noise) to about 20,000 times a second (a high-pitched whistling). (Children can generally hear higher-pitched sounds than their parents, because our ability to hear high frequencies gets worse as we get older.) Speaking more scientifically, we could say that the sounds we can perceive have a frequency ranging from 20–20,000 hertz (Hz). A hertz is a measurement of how often something vibrates and 1 Hz is equal to one vibration each second. The human voice makes sounds ranging from a few hundred hertz to a few thousand hertz.
Suppose you could somehow hit a drum-skin so often that it vibrated more than 20,000 times per second. You might be able to see the skin vibrating (just), but you certainly couldn't hear it. No matter how hard you hit the drum, you wouldn't hear a sound. The drum would still be transmitting sound waves, but your ears wouldn't be able to recognize them. Bats, dogs, dolphins, and moths might well hear them, however. Sounds this like, with frequencies beyond the range of human hearing, are examples of ultrasound.
Infrasonics, vibrational or stress waves in elastic media, having a frequency below those of sound waves that can be detected by the human ear—i.e., below 20 hertz. The range of frequencies extends down to geologic vibrations that complete one cycle in 100 seconds or longer.
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Answer:
<em>The energy level diagram is used to represent the energy states available in each atom. When an electron is in an energy state, it emits nor absorbs radiation. A photon is emitted or absorbed when an electron transitions from one energy state to another.</em>
Explanation:
Answer:
Option-B (2-methylpropene)
Explanation:
The reaction scheme is attached below,
In first step the alkene acts a nucleophile and adds H⁺ across double bond yielding a stable tertiary carbocation.
In the second step the oxygen atom of methanol acts as nucleophile and attacks the positive charge carrying carbon atom resulting in the formation of t-butyl methyl ether.
