Which statement best compares the properties of compounds and elements that the compounds contain? a. they are always identical. b. they are different. c. they are similar. d. they represent opposite characteristics.

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.)

If oil spills continue, all of the following should be expected except (2 points) death of aquatic life. polluted groundwater. decreased soil productivity. increased global temperatures.

Substance 33°f 100°f peanut oil solid liquid margarine solid liquid chocolate chips solid liquid which conclusion fits the data in the table? a. heat chemically changes chocolate and margarine. b. all solids become liquid at 100°f. c. removing heat from a substance it to melt. d. matter may change shape when it is heated.