Question

A Green coloured salt is, when heated then gives a suffocating gas. Write the chemical equation and name of the salt.

Answer 1

The nameof the salt is Ferrous Sulphate

FeSO4 (s)   Heat → Fe2O3 (s)+ SO2 (g) + SO3 (g)
        Ferrous sulphate            Ferric oxide
       Green Colored                 Reddish brown

Answer 2

Hello!

Here is your answer!
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A green salt on heating decomposes to produce a color less suffocating gas and leaves behind a reddish brown residue . 
The salt is Ferrous sulphate [ FeSO₄ ]

When Ferrous sulphate is heated it leaves a reddish brown residue [ ferric oxide --> Fe₂O₃] .

Also ,
Two gases are also evolved.
The gases are : -
Sulphur dioxide (SO₂)
Sulphur trioxide (SO₃ )

                      heat
FeSO₄ [ s ]  ----------> Fe₂O₃ [s ] + SO₂ (g) + SO₃ (g)

                        heat
2FeSO₄ [ s ]  ----------> Fe₂O₃ [s ] + SO₂ (g) + SO₃ (g)              ----> balanced equation

This is an example of decomposition reaction

As heat energy is used for this chemical reaction , this chemical reaction is also known as thermal decomposition reaction.

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Hope it helps!