4. When a key on piano is pressed, a sound is heard. What produces this sound? A. the vibrating key of the piano
B.
The Vibrating String Of Piano
C. the finger pressing the piano key
D. the air molecules inside the piano

D

Explanation:

since we press the key , air molecules ate presented and sound wave is formed what we hear.

B

Explanation:

answer: the correct answer is   air pressure at the top of mount everest is higher than at the bottom of the grand canyon.

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explanation:

the earths atmosphere is made up of nitrogen and oxygen. solids can turn into gasses through a process called sublimation. sublimation is the transition of a substance directly from the solid to the gas phase, without passing through the intermediate liquid phase.

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