Ok measure atoms the answer is B
It's the rows. They are periods. (1,2,3,4,5,6,7 - the ones without the letters).
(ANS1)— P4 + 5O2 ---> 2P2O5
(ANS2)— C3H8 + 5O2---> 3CO2 + 4H20
(ANS3)— Ca2Si + 4Cl2 ---> 2CaCl2 + SiCl4
A three-carbon alkene contains two double bonds. My prediction of its molecular formula is A. C3H4.
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.
