Answer:
They can be dated using radioactive carbon. But for rocks older than 50 thousand years they look for layers of igneous rock or volcanic ash above and Bellow the layer of rock/fossil.
Blood is pumped throughout the body by your heart. Your heart is the main organ responsible for blood circulation.
1. x-ray soft tissue organs - barium
2. reduce pain and fever- acetylsalicylic acid
3. anesthetic- nitrous oxide
4. treat acne - A. benzoyl peroxide
Answer : When we mix the aqueous solutions of magnesium sulfate with chromium acetate we get the following reaction :-

It is an example of a displacement reaction that takes place. According to the OWL solubility preparation rules all the reactants are soluble and hence the reaction occurs.
The net ionic equation of the reaction is :-