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Observe the following picture a write down the chemical reaction with the explanation.

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Write scientific reason.
Elements belonging to the same group have the same valency.
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Write scientific reasons.
Lemon or tamarind is used for cleaning copper vessels turned greenish.
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Complete the process of iron rusting by filling the blanks. Suggest a way to prohibit the process.
The iron rust is formed due to........................... reaction. Different
regions on iron surface become anode and cathode.
Reaction on anode region :
`F_e(s) → Fe^(2+) (aq) +2e^-`
Reaction on anode region :
`O_2(g) + 4H^+(aq) +............................ → 2H_2 O (l) `
When Fe2+ ions migrate from anode region they react with ................... to form Fe3+ ions.
A reddish coloured hydrated oxide is formed from ............... ions. It is called rust.
`2Fe_(3+) (aq) + 4H_2O(l) → ................. + 6H_+(aq) `
A way to prevent rusting ..................................................................
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Identify the process shown in the diagram and explain it in short

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Answer the following question.
a) What is meant by corrosion?
b) Write names of any two methods of prevention of corrosion.
c) In which method, metal like copper, aluminium are coated with a thin layer of their oxides by means of electrolysis.
d) Explain this method with diagram.
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Choose the correct alternative and rewrite the following:
Iron is _____________________.
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Answer the following question:
What is corrosion? Do gold ornaments corrode? Justify.
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Anuja’s father cannot see nearby objects clearly.
(a) What is the eye defect he is suffering from?
(b) How is it corrected?
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Write a short note on Alloying.
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Observe the following picture and answer the following questions:

- What is rust?
- Write the chemical formula of rust.
- Write the reaction of oxidation of iron at the anode.
- Write the reaction of oxidation of iron at the cathode.
- What is corrosion?
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Bifocal lens is required to correct _______ defect.
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_______ is an alloy made from iron, carbon and chromium.
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Which of the following method is used to prevent the accumulation of greenish layer on brass due to corrosion?
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Corrosion of silver causes a black layer of _______.
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To prevent corrosion of iron and steel _______ method is used.
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_______ forms a green colour in the water.
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Stainless steel is an alloy of _______.
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