NCERT Solutions Class 6 Science Changes Around us

Scroll down to download pdf file

NCERT Solutions for Class 6 Science for chapter 6 Changes Around us

Question.1 

To walk through a water logged area, you usually shorten the length of your dress by folding it. Can this change be reversed?

Answer.

Yes, the length of dress can again be increased by unfolding it. Therefore, it is a reversible change.

Question.2

You accidentally dropped your favourite toy and broke it. This is change you did not want. Can this change be reversed?

Answer.

No, this change cannot be reversed.

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. 

S.No.

Change

Can be reversed(Yes/No)

1.

The sawing of a piece of wood

 

2.

The melting of ice candy

 

3.

Dissolving sugar in water

 

4.

The cooking of food

 

5.

The ripening of a mango

 

6.

Souring of milk

 

Answer. 

S.No.

Change

Can be reversed(Yes/No)

1.

The sawing of piece of wood

No

2.

The melting of ice candy

Yes

3.

Dissolving sugar in water

Yes

4.

The cooking of food

No

5.

The ripening of a mango

No

6.

Souring of milk

No

Question.4

A drawing sheet changes when you draw a picture on it. Can you reverse this change?

Answer.

If we draw a picture on a drawing sheet with a pencil, then the picture can be erased with an eraser. Therefore, we can get back the original drawing sheet. If we draw a picture on a drawing sheet with a pen, then the original drawing sheet cannot be obtained as we cannot erase ink.

Question.5

Give examples to explain the differences between changes that can or cannot be reversed.

Answer.

1. Formation of curd from milk is an irreversible change as a new product (curd) is formed. Neither any bacteria nor any change in conditions can convert curd back into milk.

2. Take a piece of paper and fold it to make a toy aeroplan We can get back the original piece of paper by unfolding it. Take the same piece of paper and draw an aeroplane on it, cut along its outline. In this condition we cannot get back the original piece of paper as pieces of paper cannot be rejoined.

3. Take some dough and make a ball. Try to roll out a chapati. After we roll out a chapati from a ball of dough, the chapati can be converted back to ball. Once we cook the chapati, it 
cannot be converted back to ball.

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 immobilised. Can the change in POP be reversed?

Answer.

No, the change in POP cannot be reversed. Plaster of Paris (POP) has a property of setting into a hard mass on wetting with water due to the formation of a new compound called gypsum. Once the POP is hardened, it cannot be converted back into POP. Hence, it is an irreversible change.

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.

Cement sets into a hard mass on mixing with water. The hard mass obtained cannot be converted back to cement. Therefore, It is essential to keep cement away from rain otherwise it will change into a hard mass which is of no use.

Tags: 

Click on the text For more study material for Science please click here - Science

Latest CBSE News

  • CBSE board exams are going to be conducted in the next few months, and students are trying their best to get the good marks in the examination. Even though students studying in CBSE schools put maximum effort, mathematics subject alone remain a nightmare for many CBSE students till now. To help their students in the proper way, school teachers and mathematics experts are giving good advice to the...
  • Central Board of Secondary Education (CBSE) is planning to conduct the board exams for the class 10th and 12th students in the upcoming February. The CBSE board is planning to release the timetable for the exams soon. Now, the mindset of every student is to score the good works in the examination. Not all the hard working students will get the top marks in the examination. The one who studies...
  • Many CBSE students who are all preparing for their Class X exams do not prepare well for the English exams because they always try to focus on the mainstream subjects. When they are on the go for scoring more marks for the main subjects, their performance level and the marks got greatly reduced in English. English is a global language, so it is very important to learn that subject as it can help...
  • Is your child carrying a heavy school bag daily which causes pain in his shoulders and back ? See the allowed weight limits of school bag below
  • On Friday, Bihar School Examination Board (BSEB) has announced the board exam date sheet. According to the news, the exam for the matriculation and intermediate schools will be held next year. The board has also announced the date of the exams. According to the circular from the Bihar School Examination Board (BSEB), the matric exams will be held from 21/02/2019 to 28/02/2019, and the...
  • With the latest technology and smartphones at the fingertips, students will get distracted easily these days. With the plenty of interesting things around, it is very hard for the students to focus on their studies. The lapse in concentration during the studies is something very similar to online shopping. We aim at a specific product, and with the suggestions of different products on the website...
  • On the one hand, students enjoy a lot while solving the problems on the mathematics subject. On the other hand, some students cry out when they prepare for their exam. Getting a good mark in the mathematics exam is not that difficult but many students didn't recognize it. The biggest problems in mathematics exam which a student normally face during the exam are timing, getting wrong answers in...