GSEB Class 6 Science Solutions Chapter 6 Changes Around Us

Question 1. To walk through a waterlogged area, you usually shorten the length of your dress by folding it. Can this change be reversed?
Answer: Yes, this change can be turned back. You can make the dress long again simply by unfolding it.
In simple words: Yes, you can unfold your dress and make it long again.

Exam Tip: Changes like folding clothes are physical changes that can usually be easily undone.

Question 2. You accidentally dropped your favorite toy and broke it. This is a change you did not want. Can this change be reversed?
Answer: No, this change (breaking of the toy) cannot be turned back. Once a toy is broken, it's hard to make it whole like it was before.
In simple words: No, once a toy is broken, you cannot easily make it new again.

Exam Tip: Breaking an object often leads to an irreversible change, meaning it cannot return to its original state easily.

Question 3. Some changes are listed in the following table. For each change, write in the blank column, whether the change can be reversed or not.
Answer: (The specific changes were not provided in the original question, so we provide common examples for each answer.)
1. Making curd from milk: No
2. Inflating a balloon: Yes
3. Melting an ice cube: Yes
4. Burning a candle: No
5. Baking bread: No
6. Sharpening a pencil: No
In simple words: Some changes like making curd or burning things cannot be reversed, but others like blowing up a balloon or melting ice can be.

Exam Tip: Understand the basic difference between physical changes (often reversible) and chemical changes (often irreversible).

Question 4. A drawing sheet changes when you draw a picture on it. Can you reverse this change?
Answer: No, you cannot obtain a completely clean drawing sheet once a picture is drawn on it using paint, oil, or watercolors. However, you can change the drawing if a soft pencil is used to draw the picture initially.
In simple words: You can't get a completely new paper after drawing with paint. But if you used a pencil, you might erase and change it.

Exam Tip: The reversibility of drawing depends on the medium used; pencil marks are often reversible, while paint or ink marks are usually not.

Question 5. Give examples to explain the difference between changes that can or cannot be reversed.
Answer: Changes are typically divided into two main categories: reversible and irreversible. A reversible change is a process that can be turned around, allowing the original substances to be recovered or the original state to be restored. For instance, melting an ice cube into water is a reversible change because you can refreeze the water to make ice again. Similarly, inflating a balloon is reversible as you can let the air out, and the balloon returns to its original size. On the other hand, an irreversible change is a process that cannot be easily reversed to restore the original state or substances. For example, burning wood into ash is an irreversible change because you cannot turn ash back into wood. Baking a cake from flour and other ingredients is also irreversible, as the cake cannot be changed back into its original raw components.
In simple words: Reversible changes can go back to how they started, like melting ice or blowing up a balloon. Irreversible changes cannot go back, like burning wood or baking a cake.

Exam Tip: When providing examples, choose clear and common phenomena that distinctly show whether the original substance or state can be recovered.

Collapsing and opening up of Mimosa leaves represent a reversible change.

Question 6. A thick coating of a paste of Plaster of Paris (POP) is applied over the bandage on a fractured bone. It becomes hard on drying to keep the fractured bone immobilized. Can the change in POP be reversed?
Answer: No, the change in Plaster of Paris cannot be turned back once it hardens. This is because it goes through a chemical change, forming a new, solid substance.
In simple words: No, POP hardening is a chemical change, so it cannot be reversed.

Exam Tip: Chemical changes often involve the formation of new substances and are typically irreversible, unlike physical changes.

Question 7. A bag of cement lying in the open gets wet due to rain during the night. The next day the sun shines brightly. Do you think the changes, which have occurred in the cement, could be reversed?
Answer: No, these are irreversible chemical changes. Once cement gets wet and then dries, it undergoes a chemical reaction that makes it hard, and it cannot return to its original powdery form.
In simple words: No, once wet cement dries, it becomes hard and cannot go back to being powder because of a chemical change.

Exam Tip: The setting and hardening of cement are classic examples of irreversible chemical changes that are crucial in construction.