NCERT 6th Class (CBSE) Science: Sorting Materials into Groups

Question: Describe an experiment to prove that water is transparent.

Answer: Take a beaker half-filled with clean water. Put a coin in beaker of water. Place the beaker undisturbed for a few minutes where enough light is present. Now, observe the coin immersed in water from the top of the beaker. Are you able to see the coin? You can clearly see the coin immersed in water. This proves that water is a transparent liquid.

Question: Write an experiment to show that our palm is translucent.

Answer: Cover the glass of a torch with your palm at a dark place. Switch on the torch and observe from the other side of palm. We see that the light of torch passes through palm but not clearly. This experiment shows that our palm becomes translucent when a strong beam of light passes through it.

Question: How can you show that some solids like sugar, salt are soluble in water whereas solids like chalk powder and sand are not soluble in water?

Answer: Collect samples of sugar, salt, chalk powder and sand. Take four beakers. Fill each one of them about two-third with water. Add a teaspoonful of sugar to the first beaker, salt to the second, chalk powder to the third and sand to the fourth. Stir the contents of each beaker with a spoon / stirrer.

Wait for a few minutes and observe what happens to the substances added to the water.

Note down your observations in the following table.

Inference:

1.  Sugar and salt are soluble in water.
2.  Chalk powder and sand are insoluble in water.