Question 26
Are the following examples a chemical or physical changes?
Column A.
1. A sliver spoon tarnishing
2. Blowing a dandelion
3. Building a sand castle
4. Toasting bread
Column B.
A. Chemical change
B. Physical change
Column A:
1. A silver spoon tarnishing - Chemical change
2. Blowing a dandelion - Physical change
3. Building a sand castle - Physical change
4. Toasting bread - Chemical change
Column A:
1. A silver spoon tarnishing - A chemical change
2. Blowing a dandelion - A physical change
3. Building a sand castle - A physical change
4. Toasting bread - A chemical change
Column B:
1. A - Chemical change
2. B - Physical change
To determine whether the examples in Column A represent chemical or physical changes, you need to understand the difference between the two.
A chemical change is a process that results in the formation of new substances with different properties. It usually involves a molecular or atomic rearrangement. A physical change, on the other hand, is a process that does not change the chemical composition of a substance; it only alters its physical state or appearance.
Now, let's analyze each example:
1. A silver spoon tarnishing: Tarnishing occurs when the silver spoon reacts with substances in the environment, such as sulfur compounds. This reaction forms a new substance called silver sulfide. Since a new substance is formed, this is a chemical change. So, the answer for this example is (A) Chemical change.
2. Blowing a dandelion: When you blow a dandelion, its tiny seeds are dispersed into the air. However, there is no change in the chemical composition of the dandelion or the seeds. Therefore, this is a physical change. So, the answer for this example is (B) Physical change.
3. Building a sandcastle: Building a sandcastle involves physically arranging grains of sand into a specific shape. The sand grains themselves don't undergo any chemical reactions or change in composition. Thus, it is a physical change. So, the answer for this example is (B) Physical change.
4. Toasting bread: Toasting bread involves heating it in a toaster or an oven. During this process, the heat causes a chemical reaction called the Maillard reaction, which changes the composition and properties of the bread. Therefore, it is a chemical change. So, the answer for this example is (A) Chemical change.
To summarize:
1. A silver spoon tarnishing: Chemical change (A)
2. Blowing a dandelion: Physical change (B)
3. Building a sandcastle: Physical change (B)
4. Toasting bread: Chemical change (A)