Advertisements
Advertisements
Question
Write scientific reasons.
Lemon or tamarind is used for cleaning copper vessels turned greenish.
Advertisements
Solution
- Copper vessels turned greenish due to the formation of copper carbonate layer.
- The citric acid present in the lemon or tamarind neutralizes the basic copper carbonate and dissolves the layer.
- That is why tarnished copper vessels are cleaned with lemon or tamarind juice to give the surface of the copper vessel its characteristic lustre.
APPEARS IN
RELATED QUESTIONS
What is an alloy?
Give two examples of alloys with their chemical composition.
Why do we apply paint on iron articles?
Explain the terms Corrosion
What are alloys?
Give reasons:
Platinum, gold and silver are used to make jewellery.
What is anodising? Give its applications.
Write a chemical equation to show the process of corrosion of iron.
What type of chemical reaction is involved in the corrosion of iron?
State two conditions for the rusting of iron.
Fill in the following blank with suitable word:
The process of depositing a thin layer of zinc on iron articles is called .............
Explain why, through aluminium is more reactive than iron, yet there is less corrosion of aluminium when both are exposed to air.
Name any two metals which do not corrode easily.
What is the corrosion of iron known as?
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.
Name five methods of preventing rusting of iron.
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?
Name a common metal which is highly resistant to corrosion.
A common metal which is highly resistant to corrosion is:
(a) iron
(b) copper
(c) aluminium
(d) magnesium
State under what conditions corrosion is faster ?
Corrosion can be an advantage in some case.Explain ?
Find the odd man out:
Answer the following question:
What is corrosion? Do gold ornaments corrode? Justify.
Answer the following question.
List two properties of alloys.
Give reason.
A wooden article should be polished.
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.
Stainless steel is an alloy of _______.
Find the odd one out and give its explanation.
Match the columns.
| Group A | Group B |
| 1) Electroplating | a) Pressure cooker |
| 2) Anodising | b) Silver plated spoons |
| c) Coating of tin on copper | |
| d) Coating of Zinc on iron |
Explain concept with example/explain with the help of a balanced equation.
Corrosion
Draw a neat labelled diagram.
Electroplating
Complete flow chart given below.

Give the equation for the formation of rust.
Which among the following alloys contain mercury as one of its constituents?
The table shown below gives information about four substances: A, B, C and D.
| SUBSTANCE | MELTING POINT (K) | ELECTRICAL CONDUCTIVITY | |
| SOLID | LIQUID/ AQUEOUS | ||
| A | 295 | Good | Good |
| B | 1210 | Poor | Good |
| C | 1890 | Poor | Good |
| D | 1160 | Poor | Poor |
Identify Ionic compounds from the above given substances.
State whether the following statement is true or false:
Ships suffer a lot of damage though they are painted.
Give an example of a chemical reaction for the following situation:
Sound is produced
