Mendeleev was able to predict properties of elements that belonged in the “gapson the Periodic Table by looking at -

Starch and are common polysaccharide carbohydrates found in plants. sucrose glycogen fructose cellulose

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.)

Mary is conducting an experiment on how pollution affects plant growth. how can she ensure that her data are reliable?