How does blood flow from a person's leg back to the person's heart? A Gravity pushes the blood upward.
B Lungs pull the blood upward.
C Contracting leg muscles push the blood upward.
D Contracting heart muscles pull the blood upward.

How many grams of co(g) are there in 74.5 ml of the gas at 0.933 atm and 30o c?

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 chemical bond connecting one nucleotide with the next one along the nucleic acid chain is called a