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प्रश्न
Write scientific reason.
Coins are made from metals and alloys.
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उत्तर
- Coins are made from metals and alloys because metals and their alloys possess the property of malleability. So, they can be hammered into flat shape without breaking.
- Metals and alloys used for making coins should be corrosion resistance and bright in colour. They should also be hard and wear resistance.
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संबंधित प्रश्न
What is an alloy?
Give two examples of alloys with their chemical composition.
Why do we apply paint on iron articles?
Which of the following methods is suitable for preventing an iron frying pan from rusting?
Two methods by which rusting of iron can be prevented are ______ and ______.
Explain why rusting of iron objects is faster in coastal areas than in deserts.
Choose the correct answer from the options given below:
Heating an ore in a limited supply of air or in the absence of air at a temperature just below its melting point is known as
A. Smelting
B. Ore-dressing
C. Calcination
D. Bessemerisation
The chemical reaction involved in the corrosion of iron metal is that of:
(a) oxidation as well as displacement
(b) reduction as well as combination
(c) oxidation as well as combination
(d) reduction as well as displacement
Name the metal which is used for galvanising iron.
Fill in the following blank with suitable word:
The process of depositing a thin layer of zinc on iron articles is called .............
Fill in the following blank with suitable word:
The corrosion of copper produces a .............. coating of basic copper carbonate on its surface
What is meant by 'rusting of iron'? With the help of labelled diagrams, describe an activity to find out the conditions under which iron rusts.
What are the special properties of stainless steel?
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?
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:
(a) hydrated copper sulphate
(b) copper oxide
(c) basic copper carbonate
(d) copper nitrate
Name the metal which is a constituent of plant pigment?
Corrosion can be an advantage in some case.Explain ?
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:
Answer the following question.
List two properties of alloys.
Give reason.
Copper and brass utensils should be tinned.
Give a reason why rust turns moist red litmus blue.
Write a short note on Alloying.
Corrosion of silver causes a black layer of _______.
Pressure cooker : Anodizing : : Silver plated spoons : _______
Find the odd one out and give its explanation.
Write the name.
An alloy of copper and tin-
Write the name.
Method used to prevent corrosion of copper.
Write scientific reason.
On exposure to air, silver articles turn blackish after some time.
Explain concept with example/explain with the help of a balanced equation.
Corrosion
Complete flow chart given below.
Give preventive methods by giving examples of corrosion?
Copper objects lose their shine and form green coating of ____________.
Which among the following alloys contain mercury 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?
Give scientific reasons.
Silver amalgam is used for filling dental cavities.
