Classify the changes involved in the following processes as physical or chemical changes: (a) Photosynthesis
(b) Dissolving sugar in water
(c) Burning of coal
(d) Melting of wax
(e) Beating aluminium to make aluminium foil
(f) Digestion of food

a) Photosynthesis - chemical change

b) dissolving sugar in water -physical change

c) burning of coal- chemical change

d) melting of wax- Physcial change

e) beating of aluminum to make Almunium foil-Physical change

f) digestion of food- chemical change

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 volume increases