An atom has an oxidation number of -3 in one molecule, but it has an oxidation number of +3 in a second molecule. what can we say about the electronegativities of the other atoms that make up the two molecules?

It's oxidation number is related to its charge.

Since this atom's charge is very negative in the 1st molecule, it is more electronegative. Which means the other atom is less electronegative.

In the 2nd molecule, it has a positive charge, so THIS atom is less electronegative. Or, you can say the OTHER atom is more electronegative.

When recording a measurement we report the final value in terms of number followed by specific units. The numeral has to be reported to correct number of significant figures. The final answer must have all the known figures with one estimated digit. In order to see which number is significant we follow a set of rules. All non zero numbers are significant. Embedded zeroes are significant. In a decimal, leading zeroes are insignificant. Trailing zeroes are not significant unless present in a decimal number.

Units are the second important thing to consider while recording a measurement, units give us an idea on what the dimensions of measurement are. For example, length is measured in the units of meters, mass in thee units of grams.