This organ in the human body, about the size of your fist, is located behind the stomach. Its most important function is filtering foreign substances from the blood, as well as helping the body fight infections. What is the name of this organ?

What is the chemical symbol for gold?

What gas do plants absorb from the atmosphere during photosynthesis?

What element does the symbol Fe represent?

In its basic form, this substance is a kind of soap, but when mixed with gasoline, it forms a deadly material used in flame throwers and incendiary bombs. What is it?

What does a paleontologist study?

The first microwave ovens were created in which decade: 1970's, 1960's, 1950's, or 1940's?