16. ‘Osmosis is a special kind of diffusion’. Comment.
17. Classify the following into osmosis/diffusion
(a) Swelling up of a raisin on keeping in water.
(b) Spreading of virus on sneezing.
(c) Earthworm dying on coming in contact with common salt.
(d) Shrinking of grapes kept in thick sugar syrup.
(e) Preserving pickles in salt.
(f) Spreading of the smell of cake being baked throughout the house.
(g) Aquatic animals using oxygen dissolved in water during respiration.
Class 9 Answer
Answers
Answer:
16.Osmosis is a special kind of diffusion because in both cases there is a movement of particles from a higher concentration region to a lower concentration region. The only difference is that osmosis is applicable to the movement of the solvent only through the semi-permeable membrane where the solvent is water.
17.(a) The swelling up of a raisin on keeping in water is ‘Osmosis’ because the concentration of solutes in raisin is more than outside water. Hence, water moves inside the raisin causing the swelling up of raisin.
(b) The spreading of the virus on sneezing is Diffusion.
Due to sneezing, virus enters the air in the form of small droplets. They remain suspended in the air for a long time and move here and there in the air due to diffusion.
(c) The earthworm dying on coming in contact with common salt is ‘Osmosis’.
Earthworms die on coming contact with common salt because their skin dries out due to loss of water.
(d) The shrinking of grapes kept in thick sugar syrup is ‘Osmosis’.
This is because water will move down the concentration from higher concentration to lower concentration. this results in shrinkage of grapes.
(e) The Preserving pickles in salt is ‘Osmosis’. Salt helps to remove water from the cells and helps to preserve pickles.
(f) The spreading of the smell of cake being baked throughout the house is ‘Diffusion’. The particles of cake spread through diffusion hence, producing the smell.
(g) The aquatic animals using oxygen dissolved in water during respiration answer is ‘Diffusion’.
Aquatic animals use the oxygen dissolved in water through diffusion. The amount of dissolved oxygen also depends on temperature, amount of salts in water and pressure.