Which is a sign of a chemical change? question 6 options: paint on a freshly painted wall dries and is no longer sticky. ice cream melts when left at room temperature. vinegar is mixed with baking soda resulting in carbon dioxide bubbles. calcium chloride is dissolved in h2o and disappears.

What is the strongest intermolecular force between an nacl unit and an h2o molecule together in a solution? covalent bonding dipole-dipole force hydrogen bonding ion-dipole force

Which of these statements explains the difference between nuclear binding energy and the strong nuclear force ?

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.)