Jack tries to place magnets on the door of his refrigerator. he observes that the magnets don’t stick. he guesses that the door of the refrigerator is made of a nonmagnetic substance. what stage of scientific investigation does his guess represent?
a.
ask questions
b.
construct a hypothesis
c.
explain the results
d.
make observations

Which of the following elements would you expect to have the lowest ionization energy value? fluorine, lithium, neon, nitrogen

Modern pennies are composed of zinc coated with copper. a student determines the mass of a penny to be 2.482 g and then makes several scratches in the copper coaling (to expose the underlying zinc). the student puts the scratched penny in hydrochloric acid, where the following reaction occurs between the zinc and the hcl (the copper remains undissolved): zn(s) + 2 hcl(aq) → h2(g) + zncl(aq)the student collects the hydrogen produced over water at 25 °c. the collected gas occupies a volume of 0.899 l at a total pressure of 79 j mmhg. calculate the percent zinc (by mass) in the penny. (assume that all the zn in the penny dissolves.)

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