Because despite being natural they still harm the ozone layer and cause breathing problems, even suffocation.
Answer: A solution will be hypertonic to a cell if its solute concentration is higher than that inside the cell, and the solutes cannot cross the membrane. If a cell is placed in a hypotonic solution, there will be a net flow of water into the cell, and the cell will gain volume.
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Meaning of hypertonic: (1): having a higher osmotic pressure than a particular fluid, typically a body fluid or intracellular fluid. (2) of or in a state of abnormally high muscle tone.
Since the barium ion will be isoelectronic to the nearest noble gas, which is xenon, the electronic configuration for Ba2+ is: [Xe]