Question
Paheli kept some water in a beaker for heating. She observed that tiny bubbles appeared before the water started to boil. She boiled the water for about $5$ minutes and filled it in a bottle up to the brim and kept the bottle air tight till it cooled down to room temperature.
  1. Why did the tiny bubbles appeared?
  2. Do you think tiny bubbles will appear on heating the water taken out from the bottle? Justify your answer.

Answer

  1. Air is dissolved in water in the form of oxygen. Tiny bubbles are formed, when air present in the water escape on boiling it.
So, tiny bubbles appeared due to the evolution of air dissolved in water.
  1. No, tiny bubbles will not appear as there is no dissolved air in this water.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

A student covered a torch with red cellophane sheet to obtain red light. Using the red light she obtains a shadow of an opaque object. She repeats this activity with green and blue light. Will the colour of the light affect the shadow? Explain.
Some desert plants have very small leaves whereas some others have only spines. How does this benefit the plants?
Write four ways of conserving water.
Suggest an arrangement to store a $U$ shaped magnet. How is this different from storing a pair of bar magnets?
Observe the picture of an activity given below carried out with leaves of plants and polythene bag.

Now answer the following:
  1. Which process is demonstrated in the activity?
  2. When will this activity show better results-on a bright sunny day or a cloudy day?
  3. Mention any one precaution you must take while performing this activity.
Mention the main processes that help in the circulation of water in nature.
Have you seen any other organism besides redworms, in your pit? If yes, try to find out their names. Draw pictures of these.
Read the poem written below and then answer the questions from the information gathered from the book or elsewhere.
Blue and Green
Two bins, you mean?
Yes, they are there
to throw your waste.
But not in a hurry
Nor in a haste.
Select from waste, sieve if seems muddy
Separate all items and when they are ready
Place in a blue bin, or one that is green
For a voyage to the landfill, or for composting.
  1. Name the two kinds of waste that need to be separated from each other in two different waste bins.
  2. Name two items of waste each that need to be sent to a (a) landfill, (b) for composting.
Explain the manner in which light travels with the help of an activity.
How will you prove that air supports burning?