Q 37. Name the products obtained when (a) zinc sulphate is roasted (b) Lime stone is calcined.

Q 39. Iron nails are not rusted if kept in boiled distilled water for a long time. Explain.

Dear Student,

Your question seems to be incorrect, so I am assuming its Zinc Sulphide in place of Zinc Sulphate. If you still have any query regarding this topic, then we request you to please repost your question.

Ans(37). Please find below the Reactions involved in both the cases:

(a) Roasting of Zinc Sulphide (Zinc Blende): This reaction is held in presence of sufficient supply of Air(Oxygen).

2ZnS + 3O₂ $\underset{\mathbf{Sufficient}\mathbf{ }\mathbf{supply}\mathbf{ }\mathbf{of}\mathbf{ }\mathbf{Air}}{\overset{\mathbf{Roasting}}{\mathbf{\to }}}$ 2ZnO + 2SO₂

(b) Calcination of Limestone (CaCO₃): This reaction is held in absence of Air(Oxygen).

CaCO₃ $\underset{\mathbf{Absence}\mathbf{ }\mathbf{of}\mathbf{ }\mathbf{Air}}{\overset{\mathbf{Calcination}}{\mathbf{\to }}}$ CaO + CO₂

Ans(39). For rust formation to take place the iron should come in contact with oxygen in the presence of moisture to form the oxides of iron. When water is boiled the dissolve gases including Oxygen is given out and the water is left with no free oxygen molecules. As there is no reactive oxygen in contact with iron it does not rust.

Hope this information clears your doubts about the topic.

Looking forward to hear from you again!

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