Can some one please help me

Different isotopes indicate that an element will have different numbers of

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

According to the kinetic-molecular theory, what happens to a liquid when it is transferred from one container to another? the volume and the shape stay the same. the volume increases to fill the new container, but the shape stays the same. the volume stays the same, but the shape changes to fit the new container. the volume and the shape change to fill the new container.