Advertisements
Advertisements
Question
Why does a lump of cotton wool shrink in water?
Advertisements
Solution
A lump of cotton wool shrinks when immersed in water. This is because air present in the cotton wool escapes. Thus, the volume of the cotton wool decreases.
RELATED QUESTIONS
A fuel when used releases least amount of pollutants in the air.
Statement given below is incorrect. Write the correct statement :
Carbon dioxide gas allows the earth to radiate out heat rapidly.
Statement given below is incorrect. Write the correct statement :
Symbiotic bacteria are present in nodules of cereal plants such as wheat.
Statement given below is incorrect. Write the correct statement :
Potassium nitrate on strong heating decomposes into potassium nitrite and nitrogen gas.
The diagrams below represents an experiment to show the presence of a component of air.

- State why air is sucked from – outlet ‘B’ and not from outlet “A”
- State why the air is sucked ‘slowly’ from the outlet “B”
- State the observation seen after completion of the experiment.
- State the reason for the above observation seen.
- Name another component which if present in air as a pollutant would have given a similar observation
Complete the statement given below by filling in the blank with the correct word from the words given:
The product formed which is common to both combustion and respiration is ______.
Nitrogen is used in the food packaging industry because it _____.
All living things use oxygen for breathing.
Boojho took an empty plastic bottle, turned it upside down and dipped its open mouth into a bucket filled with water. He then tilted the bottle slightly and made the following observations.
- Bubbles of air came out from the bottle.
- Some water entered the bottle.
- Nitrogen gas came out in the form of bubbles and oxygen got dissolved in water.
- No bubbles formed, only water entered the bottle.
Which observations is/are correct?
Make sentences using the given set of words.
99%, oxygen, nitrogen, air, together
