3.311x divided by 10^25 particles= ? moles

5.5 moles of given substance.

Explanation:

The given problem can be solved by using the Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

The number 6.022 × 10²³ is called Avogadro number.

For example,

18 g of water = 1 mole = 6.022 × 10²³ molecules of water

1.008 g of hydrogen = 1 mole = 6.022 × 10²³ atoms of hydrogen

Solution:

3.311 ×10²⁵ / 6.022 × 10²³ = moles

5.5 moles of given substance.

the answer for sodium is 0.186

the answer for rubidium is 0.251