2.A sample of lithium has 3.4x1023 particles, how many moles are present?

The answer to your question is 0.56 moles

Explanation:

Data

Lithium = 3.4 x 10²³ particles

the number of moles = ?

Process

Use proportions and cross multiplication to find the answer. Remember that a mole of each substance equals 6.023 x 10²³ particles.

                  1 mol of Li 6.023 x 10²³ particles

                  x                 3.4 x 10²³ particles

                          x = (3.4 x 10²³ x 1) / 6.023 x 10²³

                          x = 3.4 x 10²³ / 6.023 x 10²³

                         x = 0.56 moles