Butterfly, squid, scallop, slug and which of these animals is most likely to form a fossil

Significant figures are digits read directly from the measuring instrument plus one more digit, which is __ by the observer.

What human activity increases beach erosion?

How many protons, electrons, and neutrons are in each of the following isotopes? a. zirconium-90 b. palladium-108 c. bromine-81 d. antimony-123