01:59:52 There are 25 elements found in living things. How many of these elements are found in some organisms but not all?
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The pressure inside a hydrogen-filled container was 2.10 atm at 21 ? c. what would the pressure be if the container was heated to 92 ? c ?

Particles vibrate in a rigid structure and do not move relative to their neighbors.

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.)