Isotopes of the same element vary from each other in their number of: neutrons

electrons

protons

Which is the layer underground where all empty spaces are filled with a combination of air and water ?

Turbo the snail moves across the ground at a pace of 12 feet per day. if the garden is 48 feet away, how many days will it take for the snail to get there?

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.)