In charging by rubbing, electrons move from one material to another because A. substances with very few neutrons have a net positive charge, so

they get the extra electrons.

O B. heavier substances get rid of electrons so they don't weigh as

much.

O C. the substance with the most protons steals electrons from the

other substance.

O D. some substances hold onto electrons tighter than other

substances, so they get the extra electrons.

D.

some substances hold onto electrons tighter than other

substances, so they get the extra electrons.

Explanation: When two substances are in contact by rubbing each other, there will be friction between them. The friction will stimulate what we called - Thermal energy. And what thermal energy does is the disrupt the bonding force or enhance it.

We can therefore conclude that some substances hold onto electrons tighter than other substances, so they get the extra electrons. Because at neutral state of the substance, the number of protons is equal to the number of electrons.

cell differentiation  is how generic embryonic  cells  become specialized  cells. this occurs  through a process called gene expression. gene expression is the specific combination of genes that are turned on or off (expressed or repressed), and this is what dictates how a  cell  functions.

explanation:

the box does not move because you need to use a force greater than 300 n. you are only using 50 n. it needs to at least be 301 n for the box to move because then it is an unbalanced force and it will move the way that the greater force is pushing it. if you use only 300 n it will be a balanced force and will not move because the force you are exerting on the   box is the same as its force.

hope this !

im sorry if i went too in depth, i am going to include a link to a video on khan academy that will explain this.   hope that you like the video and that it explains more in detail to you.

that is the link.