Identify the chemical changes from the following
I.Burning of magnesium in air
II.Tarnishing of silver spoon
III.Sublimation of iodine
IV.Electrolysis of water
Select the correct option from the following given codes

Options

A. I and II
B. I and III
C. I,II And IV
D. all of these

Answer

To identify the chemical changes from the given options, we will analyze each one based on the definition of a chemical change, which is characterized by the formation of new products through a chemical reaction.

### Step-by-Step Solution:

1. **Burning of Magnesium in Air**:
- When magnesium burns in air, it reacts with oxygen to form magnesium oxide (MgO).
- This process involves a chemical reaction where new products are formed.
- **Conclusion**: This is a chemical change.

2. **Tarnishing of Silver Spoon**:
- Tarnishing occurs when silver reacts with sulfur compounds in the air, leading to the formation of silver sulfide (Ag2S), which is black in color.
- This reaction results in the formation of a new product (Ag2S).
- **Conclusion**: This is a chemical change.

3. **Sublimation of Iodine**:
- Sublimation is the process where solid iodine transitions directly to gas without passing through a liquid state.
- This change only involves a physical state change and does not result in the formation of new products.
- **Conclusion**: This is a physical change, not a chemical change.

4. **Electrolysis of Water**:
- During electrolysis, water is broken down into hydrogen gas (H2) and oxygen gas (O2) when an electric current is passed through it.
- This process involves a chemical reaction that produces new substances (H2 and O2).
- **Conclusion**: This is a chemical change.

### Final Identification of Chemical Changes:
- The chemical changes identified are:
- I. Burning of magnesium in air (Chemical Change)
- II. Tarnishing of silver spoon (Chemical Change)
- IV. Electrolysis of water (Chemical Change)

- The only option that is not a chemical change is:
- III. Sublimation of iodine (Physical Change)

### Correct Options:
The correct options indicating chemical changes are I, II, and IV.