Which of the following is true about a change from a solid to a liquid? the particles speed up. the particles slow down. the particles remain at the same energy level. the particles get closer together.

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

fe 55.85 g/mol and h2o 18.02 g/mol.