question_answer

\[B{{a}^{2+}}\] ions are poisonous yet \[BaS{{O}_{4}}\] is given to patients prior to taking stomach X-rays.

Answer:

                 A suspension of \[BaS{{O}_{4}}\] in water (known as barium meal) is generally given to the patients when the X-ray photographs of alimentary canal are required. The salt coats the canal and X-ray can be taken. Otherwise, it is quite transparent to X-ray. Since \[BaS{{O}_{4}}\] is almost insoluble in water, it does not pass from digestive system into the circulatory system and can be, therefore, safely used.