When you are converting grams to moles, the operation that you will be doing is dividing by the molar mass to obtain the amount of moles of the given sample.
Answer:
a) Limiting: sulfur. Excess: aluminium.
b) 1.56g Al₂S₃.
c) 0.72g Al
Explanation:
Hello,
In this case, the initial mass of both aluminium and sulfur are missing, therefore, one could assume they are 1.00 g for each one. Thus, by considering the undergoing chemical reaction turns out:

a) Thus, considering the assumed mass (which could be changed based on the one you are given), the limiting reagent is identified as shown below:

Thereby, since there 1.00g of aluminium will consume 0.0554 mol of sulfur but there are just 0.0156 mol available, the limiting reagent is sulfur and the excess reagent is aluminium.
b) By stoichiometry, the produced grams of aluminium sulfide are:

c) The leftover is computed as follows:

NOTE: Remember I assumed the quantities, they could change based on those you are given, so the results might be different, but the procedure is quite the same.
Best regards.
Answer:
Rhodium is used to make electrical contacts, as jewelry and in catalytic converters, but is most frequently used as an alloying agent in other materials, such as platinum and palladium. These alloys are used to make such things as furnace coils, electrodes for aircraft spark plugs and laboratory crucibles.
Explanation:
condensation polymerization, since a byproduct of the reaction is a single molecule of water (hence condensation of water)
addition polymerization is if you add the two polymers together like blocks and should have no byproducts
esterification is when you combine an organic acid with an alcohol. Since neither of the two polymers look like acids, you can rule this out.
never heard of saponification, Im an mechanical engineer not an organic chemist