Celebrated annually on October 23 from 6:02 a.m. to 6:02 p.m., Mole Day commemorates "Avogadro's Number": 6.02 x 10 23. This number--called a mole--is a basic measuring unit in chemistry. Mole Day ...

President Donald Trump and his supporters are circulating an explosive theory: The FBI, they say, may have planted a mole, or "spy," inside the 2016 campaign to bring him down. The unverified ...