show that if there is no external force, The velocity decays exponentially from velocity to zero as time tends to infinity​

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.

It equals just about 6,300 km per hour each day an week

250✖️100 to get you answer