Corrosion

Q.

Classify the following as chemical or physical changes: Burning of paper and wood.

Q.

What is corrosion? What are the necessary conditions for corrosion?

Q.

If copper is kept open in air, it slowly loses its shining brown surface and gains a green coating. It is due to the formation of

1. copper carbonate

2. copper nitrate

3. green copper

4. copper sulphide

Q.

Which compound is formed on the surface of silver by the action of corrosion?

1. Silver sulphide

2. Silver nitride

3. Silver sulphate

4. None

Q. What is used as a drying agent in an experiment on the rusting process?

1. Zinc chloride
2. Anhydrous calcium chloride
3. Copper chloride
4. Anhydrous calcium sulphate

Q.

What is corrosion of iron called?

Q. Explain why rusting of iron objects is faster in coastal areas than in deserts.​

Q.

Question 8.

Why do the articles made of iron when placed in moist air get covered with reddish-brown, powdery substance? Is this process a physical or chemical change?

Q.

Give the chemical formula of rust

Q. The chemical composition of rust is:

1. cadmium oxide
2. sulphur dioxide
3. carbon dioxide
4. iron oxide

Q.

Can the rusting of iron nails takes occurs in distilled water? Justify your answer

Q. What is the green colour coating that forms on copper when it is exposed to the atmosphere?

1. Copper sulphate
2. Copper carbonate
3. Copper chloride
4. Copper hydride

Q.

What are the conditions necessary for rusting of iron.

Q.

If you leave a piece of iron in the open for a few days, it acquires a film of brownish substance, called rust.

(a) Do you think rust is different from iron?

(b) Can you change rust back into iron by some simple method?

(c) Do you think the formation of rust on iron is a chemical change?

Q.

What is rusting

Q.

Which compound is formed by the action of corrosion on copper?

1. Copper Sulphate

2. Copper Carbonate

3. Copper Sulphide

4. Copper Nitrite

Q.

What is corrosion explain with example?

Q. Statement I: If you leave a piece of iron in the open for a few days, it acquires a film of brownish substance, called rust.

Statement II: Rusting of iron is a chemical change.

1. Both the statements are correct.
2. Only statement II is correct.
3. Only statement I is correct.
4. Both the statement are incorrect.

Q.

Why ZnO is yellow at high temperature?

Q. The formation of brown coloured flaky layer (rust) on iron nail when kept in air for a long time is a _________.

1. physical change
2. chemical change
3. reversible change
4. fast change

Q. (e) Name a metal used in making electric cables.​
​

Q.

Silver articles become black on prolonged exposure to air. This is due to the formation of

1. carbon

2. silver sulphite

3. black silver

4. silver sulphide

Q. What effect does salt have on the rate of corrosion?

1. Speeds up the corrosion.
2. Remains same
3. Slows down the corrosion.
4. None of these

Q.

Copper oxide is heated with hydrogen to form copper metal and water. What happens to copper oxide?

1. Decomposition

2. Both oxidation and reduction

3. Oxidation

4. Reduction

Q. Corrosion of metal-lead describe giving necessary reaction, causes and its significance in environment

Q. Vishakha takes a few wire pieces made up of different metals and places them in a blue solution of copper sulphate. What changes does she observe in the colour of the solutions present in beakers I, II, and III?

1. I - Blue; II - Blue; III - Blue
2. I - Green; II - Blue; III - Green
3. I - Green; II - Blue; III - Blue
4. I - Blue; II - Green; III - Green

Q.

Classify the following change as physical or chemical:

Digestion of food.

Q.

Lead losses its luster due to

Q. A : Rusting of iron objects is faster in coastal areas than in deserts.

रेगिस्तानी क्षेत्रों की अपेक्षा समुद्रतटीय क्षेत्रों में लोहे की वस्तुओं में जंग लगने की दर तीव्र होती है।

R : Greater is the humidity, faster is the rate of formation of rust.

आर्द्रता अधिक होने पर जंग के बनने की दर तीव्र हो जाती है।

1. Both (A) and (R) are true and (R) is the correct explanation of (A)
   
   (A) तथा (R) दोनों सही हैं तथा (R), (A) का सही स्पष्टीकरण है
2. Both (A) and (R) are true but (R) is not the correct explanation of (A)
   
   (A) तथा (R) दोनों सही हैं लेकिन (R), (A) का सही स्पष्टीकरण नहीं है
3. (A) is true but (R) is false
   
   (A) सही है लेकिन (R) गलत है
4. (A) is false but (R) is true
   
   (A) गलत है लेकिन (R) सही है

Q.

Why silver turns into black after a long time? Give the reason.