You have been given a sample of an unknown

substance. You find out that it does not

dissolve in water, has a very high melting

point and conducts electricity when molten.

The substance is probably

1. C8H18

2. an ionic compound

3. sodium chloride

4. a covalent compound

At first I thought it would be an ionic compound, but it says that it doesn't dissolve in water so im not too sure about it.

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.)