I need help on my homework

Magnesium ribbon

Explanation:

The mole of a substance is a quantity  that contains the Avogadro's number of particles.

 This Avogadro's number of particles  = 6.02 x 10²³particles

It is known that 1 mole of any substance contains 6.02 x 10²³particles

So, from the given choices, the object with the highest number of moles will contain the highest amount of particles.

   Magnesium ribbon with 0.871mole will contain the highest number of particles;

   Number of particles  = 0.871 x 6.02 x 10²³particles  = 5.24 x 10²³particles

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)