{b} In experiment B. the iron filings weighed 2.0g at the beginning of the experiment
and the iron sulphide produced weighed 2.8g.
Explain this increase in mass.

Layers of rock containing fossils, like the layers illustrated here, are most likely composed of rocks.

Select the correct text in the passage. which sentences describe examples of sustainable living? i live in an old apartment building downtown, but my company is based in an office park on the outskirts of the city. i drive an old car that needs to be replaced. i plan to buy a hybrid for better gas mileage, but for now i am able to carpool with a couple of friends from work. the drive to the office park is about 45 minutes each way, but we do get to work in a modern building. the architects just received a leed certification for the design.

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.)