Question

How many particles are present in a sample with mass of 107.75 g that contains 30% He and 70% Kr?

Answer 1

find moles of each using: \(n=\dfrac{m}{M}\) ; where, m=mass, n=moles, M=molar mass

then find particles, using:\(n=\dfrac{N}{N_A}\)

where, N=particles (eg. atoms), \(N_A\)=avogadros number, n=moles