In the experiment for determining the percentage of water absorbed by raisins, we do the final weighing of the raisins after keeping them dipped in water for about one hour. For the accuracy of the result, the extra water from the surface of the soaked raisins is removed by
In the experiment for determining the percentage of water absorbed by raisins, we do the final weighing of the raisins after keeping them dipped in water for about one hour. For the accuracy of the result, the extra water from the surface of the soaked raisins is removed by
Options
The correct option is D: filter paper.
Marking Scheme
- 11 mark for identifying 'filter paper' as the correct drying agent.
Hint
We need a material that can gently absorb surface moisture without applying heat, friction, or leaving sticky fibers behind.
Quick Oral Answer
We use filter paper because it gently absorbs only the surface water by capillary action without damaging the delicate skin of the swollen raisins or causing evaporation of the absorbed water.
Analysis & Explanation
In this practical experiment, after removing the soaked raisins from water, they must be dried gently to remove only the surface water (adhering water) without squeezing out any water that has been absorbed inside.
Filter paper (or blotting paper) is highly absorbent and can gently pat the surface of the raisins dry without applying pressure or heat.
Why other options are incorrect:
- Option A: Rubbing with a cotton cloth can apply too much friction, which might rupture the delicate, swollen outer membrane (skin) of the raisins, causing the internal sugary solution to leak out.
- Option B: A hot air blower will cause the water inside the raisins to evaporate, leading to an underestimation of the actual water absorbed.
- Option C: Dry cotton wool has loose fibers that will stick to the sticky surface of the raisins, adding external weight and introducing errors in the final weighing.
Common Mistakes
- 1Students might choose cotton cloth or cotton wool, which can damage the raisins or leave fibers on them, affecting the weight accuracy.
Interesting Facts
The skin of a raisin acts as a selectively permeable membrane, allowing water molecules to enter via osmosis while preventing the sugars inside from escaping.
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Frequently Asked Questions
How many marks does this question carry in CBSE Class 10 Science 2012?
This question carries 1 mark in the CBSE Class 10 Science 2012 examination.
Which chapter does this question come from in Science?
This question is from the chapter "Life Processes" in the CBSE Class 10 Science syllabus.
What topic does this question cover in Science?
This question covers the topic "Osmosis and Water Absorption in Raisins" from CBSE Class 10 Science.
What type of question is this in the CBSE Class 10 Science 2012 paper?
This is a MCQ question from Section B in the CBSE Class 10 Science 2012 paper.