What has been most challenging part about this year when it came to your academics? write in full sentences.

In atoms, the electron carries a negative elementary or unit charge; the proton carries a positive charge. the two types of charge are equal and opposite. in an atom of matter, an electrical charge occurs whenever the number of protons in the nucleus differs from the number of electrons surrounding that nucleus.

Because there is no air in the jar, the vibrations can not travel through the air and create sound.  (that's why there is no sound in space, there is no air)

Electrons have a negative charge if that's what you're asking