An LD50 of 20 in mice indicates that Question 18 options: 50% of a test population of 100-kg mice would be expected to die within a certain time period if exposed to 20 g 50% of a test population of 100-g mice would be expected to die within a certain time period if exposed to 2 mg 50% of a test population of 100-kg mice would be expected to die within a certain time period if exposed to 20 ppm of the vapor