Which of the following are not chemical changes ? 1. Tempering of iron 2. Conversion of iron piece into an electro-magnet by passing the current around the iron 3. Melting of iron 4. Rusting of iron Select the correct answer using the code given below :

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Q: 105 (CAPF/2014)

Which of the following are not chemical changes ?
1. Tempering of iron
2. Conversion of iron piece into an electro-magnet by passing the current around the iron
3. Melting of iron
4. Rusting of iron
Select the correct answer using the code given below :

question_subject: 

Geography

question_exam: 

CAPF

stats: 

0,28,38,21,9,28,8

keywords: 

{'chemical changes': [0, 0, 0, 1], 'iron': [0, 0, 1, 1], 'iron piece': [0, 0, 0, 1], 'rusting': [0, 0, 4, 1], 'magnet': [0, 0, 2, 6], 'current': [0, 0, 0, 3], 'melting': [0, 0, 0, 1], 'afld': [0, 0, 0, 1], 'electro': [0, 0, 0, 2], 'conversion': [3, 1, 3, 6]}

The correct answer is option 3: 1, 2, and 3.

To better understand why these options are not chemical changes, let`s dissect each one:

1. Tempering of iron: Tempering involves heating and cooling iron to improve its hardness and toughness. It does not involve a chemical reaction, but rather a physical change in the arrangement of the iron`s atoms.

2. Conversion of iron piece into an electro-magnet by passing the current around the iron: This process is known as electromagnetism, where the passage of electric current generates a magnetic field around the iron. It is also a physical change and does not involve any chemical reactions.

3. Melting of iron: Melting involves applying heat to change a solid into a liquid. In this case, iron changes from a solid state to a liquid state, but no chemical reactions occur. It is purely a physical change.

4. Rusting of iron: Alert - correct answer should be option 2: 3 and 4 only. Rusting is a chemical change that occurs when iron reacts with oxygen and water in the presence of moisture, resulting in the formation of iron oxide. This is a prime example of a chemical change.