Order the following atoms and /or ions based on decreasing atomic and /or ionic radius: (a) K, Li, Na
(b) As, N, P
(c) B, C, N
(d) Rb, Rh, Ru
(e) K, K^+1, K^-1
(f) Br^-1, Br, Br^+1

1. 1 mole of anything contains 6.022x10^23 pieces  

d  

2. a  

3. c, number  

5. 1.24x10^24atoms / 6.022x10^23atoms/mole = 2moles h2 atoms  

6. fe2br3 mass = 2moles x mass fe + 3 moles x mass br  

molar mass = grams / number of moles = g/mole  

to find moles = g / molar mass  

to find mass = g = molar mass / moles

the answer to this question is 3.