Question

which of the following should you do when you perform this experiment?
handle the crucible with your bare hands
check the crucible for any fractures or cracks
set a hot crucible directly on the bench
leave the lid on the crucible for the entirety of the reaction
question 4
which of the following would be considered an empirical formula?
c₆h₆
no₂
c₂h₄n₂
c₂h₅

Explanation:

1. For the first question, handling a crucible with bare hands can cause burns, setting a hot crucible directly on the bench can damage the bench and cause safety - hazards, and leaving the lid on throughout the reaction may affect the reaction process. Checking for fractures or cracks in the crucible before use is a proper safety and experimental - integrity measure.
2. For the second question, an empirical formula represents the simplest whole - number ratio of atoms in a compound. $C_6H_6$ can be simplified further, $C_2H_4N_2$ can be simplified, and $C_2H_5$ is not the simplest ratio for a common compound. $NO_2$ is already in its simplest whole - number ratio of atoms.

Answer:

1. Check the crucible for any fractures or cracks
2. $NO_2$