derive an expression for the work required by an external agent to put the four charges together as indicated in fig.25 each side of the square has length a

Your answer is c. explanation: plasma  is the fourth state of matter, derived from the gaseous state of matter.  plasma  can contain free  electrons  and/or  ions. while  plasma is never neutral, it can either be positively or negatively charged.  gases, however, are electrically neutral.

I’m not sure about this question

Hey kylee the answer is d.

The answer is d hope i . : )