To be written in scientific notation, the first number or the number being multiplied by 10^# must be written like this Ex. 1.0 2.0 3.0 etc. In other words it must have one and only one digit to the left of the decimal and answer choice D is the only answer choice that meets the criteria.
I'm pretty sure it's chemical because the calcium carbonate from the vinegar gets into the eggshell making a reaction change the entire display of the shell making it disappear.
