Infrared radiations are primarily used to a. heat food in ovens b. transmit cellular phone signals c. image people's bones and teeth d. detect the location of objects that emit heat

an ion is a charged atom or molecule. it is charged because the number of electrons do not equal the number of protons in the atom or molecule. an atom can acquire a positive charge or a negative charge depending on whether the number of electrons in an atom is greater or less then the number of protons in the atom.