How many neutrons are present in an atom of tin that has an atomic number of 50 and a mass number of 119?

Acylinder is filled with 2.00 moles of nitrogen, 3.00 moles of argon and 5.00 moles of helium. if the gas mixture is at stp, what is the partial pressure of the argon

Determine the number o moles of ions/atoms/particle in the following: 2.50 miles of k2s (let me know how to do)

The wave shown on the electromagnetic spectrum disturb the medium it passes through a)different frequency. b)the same frequency .