Some of what I have read here leads me to believe that a TIA is a stroke that totally reverses itself and all symptoms go away within 24 hrs. Other postings indicate that if symptoms continue or periodically return, then that is an indication that it was more than just a TIA or that there are continuing problems.
Chalk /ËtÊÉËk/ is a soft, white, porous sedimentary carbonate rock, a form of limestone composed of the mineral calcite. Calcite is calcium carbonate or CaCO 3.It forms under reasonably deep marine conditions from the gradual accumulation of minute calcite shells (coccoliths) shed from micro-organisms called coccolithophores.he most common forms are CaCO 3 (calcium carbonate) and CaO (calcium oxide). Small doses of chalk can also be used as an antacid. Additionally, the small particles of chalk make it a substance ideal for cleaning and polishing.
  chalk is made from substances in the earth, (which i don't know the name of) and it is a weak rock that we always see in class,(depends if your teacher is a smartboard â¦ or Geniusboard user or uses marker). Chalk is used for writing, lawn tennis, gymnastics, and toothpaste. 4 people found this useful. Answered.