What is the molarity of a solution prepared by dissolving 12.0 g of potassium permanganate, KMnO4, in water to make 250.0 mL of solution

What is the ph of a 0.0010 m hno3? 1.0 3.0 4.0 5.0

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.)

Is a pencil falling to the floor anon contact force, a force, or a contact force