18.The Halogen family of elements all have 7 valence electrons. Which column would they be in? a.01 (IA)
b.02 (IIA)
c.4 (IVA) or 14
d.7 (VIIA) or 17

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.)

What is the percentage of hydrogen in c2h4

Determine the osmotic pressure at 25 °c of an aqueous solution that is 0.028 m nano3. a) 0.685 atm b) 0.0729 atm c) 1.37 atm d) 0.0364 atm e) 2.06 atm