An isotope used for absolute dating has a half-life of 100,000 years. Laboratory analysis of a crystal, which originally formed with only the parent isotope present, is now found to have a parent-to-daughter ratio of 1 :3. How long has it been since the crystal formed? * A. 33,000 years
B. 50,000 years
C. 200,000 years
D. 300,000 years

Which statement describes an endocrine function rather than an exocrine function? a. salivary glands release saliva into the mouth. b. sweat glands release sweat onto the skin c. the pineal gland releases melatonin into the blood. d. esophageal glands release mucus into the esophagus.

Which of the following types of stars is most likely to end up as a supernova? in graph a, the curve peaks at 800 nm, in the red section of the visible light spectrum. in graph b, the curve peaks at 550 nm, in the green section of the visible light spectrum. in graph c, the curve peaks at 450 nm, in the blue section of the visible light spectrum. in graph d, the curve peaks at 300 nm, in the violet section of the visible light spectrum. a b c d

Which statement does lola need to correct, and why? a) statement 1 because spiral galaxies do not havearmsb) statement 2 because the bulges contain mostlyyoung red stars. c) statement 3 because the arms are made of mostlyyoung blue and blue-white stars. d) statement 4 because spirals galaxies contain littleto no dust.(c)