A plastic rod rubs against a cloth and the cloth becomes negatively charged. Which of the following statements are true?

Ithink your answer is d

It indicates no change in temperature and the process of matter changing its state

The answer is 4f======since electrostatic force is given by    we let f be the electrostatic force when  r = 1 m    if we let  denote the electrostatic force when the distance is decreased so that r = 0.5m, then    we established earlier that f = kq₁q₂. therefore    the force will now be 4f.

Chromium  +  hydrogen sulfate  =  chromium(iii) sulfate  +  hydrogenso then it will be  a. cr + h2so4? cr2(so4)3 + h2