The heat of hydrogenation of an unsaturated compound can be used to estimate its stability. The heat of hydrogenation of benzene is than expected by comparison with cyclohexene and 1,3-cyclohexadiene. This difference indicates that benzene is much stable than a system containing three isolated double bonds.

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.)

The human activities in two locations are described below: location a: rampant use of plastic containers location b: excessive use of pesticides and fertilizers which statement is most likely true? location a will have poor air quality because plastic is biodegradable. location a will experience water scarcity because plastic absorbs moisture. the population of honeybees will increase in location b because production of crops will increase. the population of fish in location b will decrease because the water is contaminated.

Heat energy, carbon dioxide, and water are released through which process? a. photosynthesis b. depolymerization c. digestion d. cellular respiration