Answer:
0.05%
Step-by-step explanation:
That's because it's a hypotonic solution. It's solute concentration is lower than than of the cells' contents. So water diffuses in, down the concentration gradient, across a partially permeable membrane via osmosis. This exerts more pressure on the relatively weak cell membrane and cause the cell to swell then burst.
It's less than 0.9% which is the isotonic solution.