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Author Question: The half-life of a radioactive element is the amount of time it takes for ____________________ of ... (Read 75 times) |
Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.
The heart is located in the center of the chest, with part of it tipped slightly so that it taps against the left side of the chest.
Vampire bats have a natural anticoagulant in their saliva that permits continuous bleeding after they painlessly open a wound with their incisors. This capillary blood does not cause any significant blood loss to their victims.
During the twentieth century, a variant of the metric system was used in Russia and France in which the base unit of mass was the tonne. Instead of kilograms, this system used millitonnes (mt).
Approximately 500,000 babies are born each year in the United States to teenage mothers.