Does a given type of nucleus always have the same half-life?

How would you reduce the volume of gas

Gymnast always perform on padded mats. how does the mats protect the gymnast

Which of the following describes a compound? (hint: carbon and oxygen bo a. a piece of pure carbon, containing only carbon atoms b. oxygen gas surrounding a solid piece of carbon c. a substance made of two oxygen atoms for each carbon atom carbon and oxygen atoms mixed without being bonded together