Which of the following is NOT evidence that a chemical reaction happened? a. a color change occurred
b. bubbles formed
c. calcium chloride dissolves in water
d. reaction was cold

If a molecule with a molecular formula of c13h18 is treated with an excess of h2 in the presence of finally divided pt metal under conditions required for maximum hydrogenation of the molecule to give a molecule with a formula c13h24, how many rings are in the molecule?

Answer asap : ( a. how does mucus prevent the entry of pathogens? b. describe two ways white blood cells protect us from pathogens.

Which metals are called noble metals