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प्रश्न
Identify the process shown in the diagram and explain it in short
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उत्तर
The process shown in the diagram is Anodization.
In this method metals like copper, aluminium are coated with a thin and strong layer of their oxides by means of electrolysis. For this the copper or aluminium article is used as anode. As this oxide layer is strong and uniform all over the surface, it is useful for prevention of the corrosion of the metal.
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संबंधित प्रश्न
Tinning : Tin : : Galvanizing : _________
Why do we apply paint on iron articles?
Explain the term corrosion.
What are alloys?
Explain how painting of an iron gate prevents it from rusting.
What is anodising? Give its applications.
Explain the term “corrosion” with an example. Write a chemical equation to show the process of corrosion of iron.
What is meant by galvanisation? Why is it done?
The corrosion of iron is called ______.
The process of depositing a thin layer of zinc on iron articles is called ______.
Tiffin boxes are electroplated with ______ but car bumpers are electroplated with ______ to protect them from rusting.
With the help of labelled diagrams, describe an activity to find out the conditions under which iron rusts.
Name an alloy of copper. State its chemical composition and any one use.
Explain why, when a copper object remains in damp air for a considerable time, a green coating is formed on its surface. What is this process known as?
State under what conditions corrosion is faster ?
Explain with reason:
Roasting is carried out on sulphide ores and not on carbonate ores.
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:
Choose the correct alternative and rewrite the following:
Iron is _____________________.
Give a reason why rust turns moist red litmus blue.
Write a short note on Alloying.
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?
Corrosion of silver causes a black layer of _______.
_______ forms a green colour in the water.
When one of the metals in an alloy is mercury the alloy is called _______.
Find the odd one out and give its explanation.
Write scientific reason.
On exposure to air, silver articles turn blackish after some time.
Write scientific reason.
Coins are made from metals and alloys.
What is rust?
Observe the following figure and write the answer of the question.
- Which process is shown in the figure?
- Explain the chemical reaction shown in the figure.
- Write the reactions on anode and cathode.
The process of coating the surface of the metal with a thin layer of zinc is called ______
The diagram shows the reaction between metal and dil. acid.
What is the reason for different behaviour of Mg in test tube B?
Identify the correct statement from the following:
Give scientific reasons.
Silver amalgam is used for filling dental cavities.
Explain the chemical reactions in rusting of iron.
Describe two changes that are harmful. Explain why you consider them harmful. How can you prevent them?
