Describe the pattern of synthesis (combination) and decomposition reactions.

Explanation:

Synthesis is the combining of two elements or atoms into a compound/mixture. Decomposition is the breaking down of a compound/mixture into individual atoms or elements. In conclusion, on is the building up of a compund/mixture and one is breaking down.

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