I think this is what you wanted, so good luck!
I think the correct answer from the choices listed above is option B. The reactants calcium sulfide and sodium sulfate will react and form a precipitate which is calcium sulfate since it is only slightly soluble in aqueous solution. Hope this answers the question.
I’m going to say the answer is most likely X because memetic energy is energy being used at that moment. Because the coaster is going fastest at X we can assume that the answer is X
The SI unit for the amount of substance present is the mole.
The mole is defined as the amount of substance that has the same amount of particles as there are atoms in 12 grams of carbon-12. Mathematically, the moles of a substance may be computed using:
moles present = mass of substance / molecular mass of substance