What one factor identifies an atom as a specific element?

Two metal blocks that have slightly different temperatures are placed next to one another. after five minutes, they both have lower but equal temperatures. according to the law of conservation of energy, what  most likelyhappened? energy was created inside the blocks.energy was destroyed inside the blocks.energy was absorbed into the blocks from outside the system.energy was transferred from the warmer block to the cooler block.

Which rate indicates the number of children that would be born per woman if she were to live to the end of her child bearing years

From the choices provided below, list the reagent(s) in order that will react with cyclopentanone to form the compound shown below.