It’s because new discoveries are made all the time sometimes what was considered right may be found out to be wrong
It has mass and takes up space is correct.
I don’t know what to answer
Answer:
number of moles=volume/molar volume or mass/molar mass
Doppler effect is the compression or extension of a sound wave, which causes a change in its wavelength / frequency (and so its sound).
Explanation: It is defined as the effect produced by a moving source of waves in which there is an upward shift in frequency for observers, the source is moving towards and downward shift of frequency from which the source is moving away. used to tell if an object in space is moving toward or away from us.
