A clinical study is conducted to determine the actions of an unknown test solution on red blood cell volume. One milliliter of heparinized human blood is pipetted into 100 milliliters of test solution and mixed. Samples are taken and analyzed immediately before and at 1-second intervals after mixing. The results show that red blood cells placed into the test solution immediately swell and burst. Which of the following best describes the tonicity and osmolarity of the test solution?