I need help on these Questions.

Layers of rock containing fossils, like the layers illustrated here, are most likely composed of rocks.

Me i dont know what to do! the table compares the number of electrons in two unknown neutral atoms. comparison of electrons atom number of electrons a 10 d 11 use this information to determine the number of valence electrons in the atoms. which of the following correctly compares the stability of the two atoms? both are unreactive. both are highly reactive. a is unreactive and d is reactive. a is reactive and d is unreactive.

Avariable that is not being directly tested during an experiment should be