Which method of testing substances is a sure way to identify a chemical reaction? A.
change in color
B.
formation of bubbles
C.
change in density
D.
increase in temperature
E.
solubility in water

Based on its chemical properties, identify the position of each chemical family on the periodic table.

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.

Harry lives in a city, and he has a lung condition known as asthma. on certain days, harry has to stay inside because pollutants in the air make it difficult for him to breathe. which of these pollution sources are nonpoint sources that might bother harry if he goes outside? choose the two that apply.