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प्रश्न
Find the odd man out:
पर्याय
Tinning
Anodization
Alloying
Froth floatation
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उत्तर
Froth floatation
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संबंधित प्रश्न
What is an alloy?
Write two methods of preventing the rusting of iron.
Which metals do not corrode easily?
What type of chemical reaction is involved in the corrosion of iron?
The corrosion of copper produces a ______ coating of basic copper carbonate on its surface.
Name any two metals which do not corrode easily.
Name five methods of preventing rusting of iron.
What are the special properties of stainless steel?
Explain why, the galvanised iron article is protected against rusting even if the zinc layer is broken.
If copper is kept exposed to damp air for a considerable time, it gets a green coating on its surface. This is due to the formation of ______.
Brass is an alloy of ______.
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.
What is corrosion? What are necessary conditions for corrosion?
No chemical reaction takes place when granules of a 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.
(i) Based on the given information make an assumption about A and B and write a chemical equation for the chemical reaction indicating the conditions of reaction, physical state of reactants and products and thermal status of reaction.
(ii) Mention any two types of reactions under which above chemical reaction can be classified.
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.
What is done to prevent corrosion of metals?
What are the adverse effects of corrosion?
What is ‘rusting’?
Give reason.
A wooden article should be polished.
Give reason.
Copper and brass utensils should be tinned.
Give a reason why rust turns moist red litmus blue.
State whether the statement given below is true or false. If false write the correct statement.
Either oxygen or moisture is essential for rusting.
Bronze : _______ : : Stainless steel : Fe + Cr + C
Find the odd one out and give its explanation.
Find the odd one out and give its explanation.
Draw a neat labelled diagram.
Electroplating
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 ______
State two conditions necessary for rusting of iron.
Alloys are homogeneous mixtures of a metal with a metal or non-metal. Which among the following alloys contain non-metal as one of its constituents?
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?
A man painted his main gate made up of iron, to
- prevent it from rusting.
- protect it from sun.
- make it look beautiful.
- make it dust free.
Which of the above statement(s) is/are correct?
Iron pillar near the Qutub Minar in Delhi is famous for the following facts. Which of these facts is responsible for its long stability?
State whether the following statement is true or false:
Ships suffer a lot of damage though they are painted.
Explain the following:
Lime water turns milky on passing carbon dioxide gas into it.
| A process of forming a thick oxide of aluminium when aluminium is exposed to air. This coat makes it resistant to corrosion. Resistance can be improved by making a layer of oxide thinker. In this technique, the aluminium article is the anode, and the electrolyte is sulphuric acid. The anode reaction results in the formation of a black-coloured film of aluminium oxide on the anode. By putting appropriate dyes in the electrolytic solution, both coloured surface with the decorative finish is achieved. Kitchen articles like anodised such as pressure cookers, pans and frames of sliding windows are applications of this technique. |
- Name the anode and electrolyte used in this technique.
- How can we make aluminium articles made resistant to corrosion?
- Name the technique used to coat the aluminium articles.
Describe two changes that are harmful. Explain why you consider them harmful. How can you prevent them?
