Which radioactive isotope is commonly used to date wooden artifacts?

Ants live on acacia trees in south america. the ants feed on sugars secreted by the trees. the trees provide room for the ants to live. the ants sting any other insect or animal that comes to eat the trees. what type of relationship is this?

How does the presence of oxygen affect the chemical pathways used to extract energy from glucose?

Why is the melting of ice a physical change ?