Classify the following as chemical or physical changes :
`**` cutting of trees.
`**` melting of butter in a pan,
`**` rusting of almirah,
`**` boiling of water to form steam,
`**` passing of electric current, through water and the water breaking down into hydrogen and oxygen gases.
`**` dissolving common salt in water,
`**` making a fruit salad with raw fruits, and
`**` burning of paper and wood.