I'm assuming that you are asking a general question because you did not include an example.
The limiting reagent is the item in the reactants (reagents) that will run out first. This is because it limits what the reaction can produce, essentially causing the leftover elements/compounds to just sit there.
Distance travelled will be equal to displacement when the line drawn is completely straight.
Hopefully, this helps.
Hm I’m confused, if you mean what are they weighting, it’s they :)
6) Na2 SO4
7)nonmetallic elements
10)mass
11) mole
* sorry I didn't know Q. 8/9