Class 9 activity 1.8 observation matter in our surroundings
Answers
Explanation:
Take a 100 mL beaker.
Fill half the beaker with water and mark the level of water.
Dissolve some salt/ sugar with the help of a glass rod.
Observe any change in water level.
What do you think has happened to the salt?
Where does it disappear?
Does the level of water change?
Solution:
(a) Salt is dissolved in water
(b) Particles of salt filled in the gaps between the particles of water.
(c) No, there is no change in level of water.
This activity shows that,
Matters are made of small particles. And there is space between these particles.
Activity: 1.2
Take 2-3 crystals of potassium permanganate and dissolve them in 100 mL of water.
Take out approximately 10 mL of this solution and put it into 90 mL of clear water.
Take out 10 mL of this solution and put it into another 90 mL of clear water.
Keep diluting the solution like this 5 to 8 times.
Is the water still coloured ?
Solution:
Yes water is still colored.
This happens because matter is made of very small particles, which are spread in the water.
Activity: 1.3
Put an unlit incense stick in a corner of your class.
How close do you have to go near it so as to get its smell?
Now light the incense stick. What happens?
Do you get the smell sitting at a distance?
Record your observations.
Solution :
One has to go very close to get the smell of the unlit incense stick.
After lighting the incense stick, smoke started to coming out of it.
Answer:
Take a 100 mL beaker.
Fill half the beaker with water and mark the level of water.
Dissolve some salt/ sugar with the help of a glass rod.
Observe any change in water level.
What do you think has happened to the salt?
Where does it disappear?
Does the level of water change?