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प्रश्न
Answer the following question:
What is corrosion? Do gold ornaments corrode? Justify.
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उत्तर
- The slow process of decay or distinction ions of a metal due to the effect of air, moisture, acids, alkalies, or other chemicals on it is called corrosion.
- Ordinarily, gold ornaments do not get corroded.
- Gold is one of the least reactive metals. It does not react with air, moisture, sweat, or ordinary pollutants in air or water. Hence, it does not get corroded.
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संबंधित प्रश्न
What are alloys?
Two methods by which rusting of iron can be prevented are ______ and ______.
What is anodising? Give its applications.
What special name is given to the corrosion of iron?
State two conditions for the rusting of iron.
Tiffin boxes are electroplated with ______ but car bumpers are electroplated with ______ to protect them from rusting.
The corrosion of copper produces a ______ coating of basic copper carbonate on its surface.
What is the corrosion of iron known as?
Name two metals which resist corrosion due to the formation of a thin, hard and impervious layer of oxide on their surface.
A common metal which is highly resistant to corrosion is ______.
No chemical reaction takes place when granules of a rusty-brown solid A are mixed with the powder of another solid B. However, when the mixture is heated, a reaction takes place between its components. One of the products C is a metal and settles down in the molten state while the other product D floats over it. It was observed that the reaction is highly exothermic.
- What could the solids A and B be?
- What are the products C and D most likely to be?
- Write the chemical equation for the reaction between A and B leading to the formation of C and D. Mention the physical states of all the reactants and products in this equation and indicate the heat change which takes place.
- What is the special name of such a reaction? State one use of such a reaction.
- Name any two types of chemical reactions under which the above reaction can be classified.
Bronze is an alloy of ______.
Observe the following picture a write down the chemical reaction with the explanation.
Write scientific reasons.
Lemon or tamarind is used for cleaning copper vessels turned greenish.
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 ..................................................................
Find the odd man out:
What is ‘rusting’?
Explain the term – rusting and give a word equation for the formation of rust. If polished iron nails are kept in three separate test tubes, state the contents in each test tube required, to prove the conditions for rusting.
State whether the statement given below is true or false. If false write the correct statement.
Either oxygen or moisture is essential for rusting.
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?
Stainless steel is an alloy of _______.
Pressure cooker : Anodizing : : Silver plated spoons : _______
Find the odd one out and give its explanation.
Find the odd one out and give its explanation.
Write scientific reason.
Anodization method is useful for prevention of the corrosion of the aluminium.
Complete flow chart given below.
What is rust?
Observe the following diagram and give answers.
- Name this method of prevention of corrosion.
- For prevention of which metal this method is used?
- What is used as anode in this method?
The process of coating the surface of the metal with a thin layer of zinc is called ______
State two conditions necessary for rusting of iron.
Galvanisation is a method of protecting iron from rusting by coating it with a thin layer of ____________.
Amalgam is an alloy of ____________.
Identify the correct statement from the following:
Generally, when metals are treated with mineral acids, hydrogen gas is liberated but when metals (except Mn and Mg), treated with HNO3, hydrogen is not liberated, why?
Explain the following:
Lime water turns milky on passing carbon dioxide gas into it.
Give scientific reasons.
Silver amalgam is used for filling dental cavities.
Explain the chemical reactions in rusting of iron.
