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Give a reason for the following observation.
Naphthalene balls disappear with time without leaving any solid.
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Give a reason for the following observation.
We can get the smell of perfume sitting several metres away.
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Arrange the following substances in increasing order of forces of attraction between particles -
water, sugar, oxygen
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Write the steps you would use for making tea. Use the words: solution, solvent, solute, dissolve, soluble, insoluble, filtrate and residue.
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Pragya tested the solubility of three different substances at different temperatures and collected the data as given below (results are given in the following table, as grams of substance dissolved in 100 grams of water to form a saturated solution).
| Substance dissolved | Temperature in K | ||||
| 283 | 293 | 313 | 333 | 353 | |
| Solubility | |||||
| Potassium nitrate | 21 | 32 | 62 | 106 | 167 |
| Sodium chloride | 36 | 36 | 36 | 37 | 37 |
| Potassium chloride | 35 | 35 | 40 | 46 | 54 |
| Ammonium chloride | 24 | 37 | 41 | 55 | 66 |
- What mass of potassium nitrate would be needed to produce a saturated solution of potassium nitrate in 50 grams of water at 313 K?
- Pragya makes a saturated solution of potassium chloride in water at 353 K and leaves the solution to cool at room temperature. What would she observe as the solution cools? Explain.
- Find the solubility of each salt at 293 K. What salt has the highest solubility at this temperature?
- What is the effect of change of temperature on the solubility of a salt?
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Identify the solutions among the following mixtures.
- Soil
- Sea water
- Air
- Coal
- Soda water
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Fill in the gaps in the following table, illustrating differences between prokaryotic and eukaryotic cells.
| Prokaryotic cell | Eukaryotic cell | ||
| 1. | Size: generally small (1–10 µm) 1 µm = 10-6 m | 1. | Size: generally large (5-100 µm) |
| 2. | Nuclear region: ____________ ____________ and is known as _____. |
2. | Nuclear region: well defined and surrounded by a nuclear membrane. |
| 3. | Chromosome: single | 3. | More than one chromosome |
| 4. | Membrane-bound cell organelles absent |
4. |
____________ |
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How is a prokaryotic cell different from a eukaryotic cell?
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How does an Amoeba obtain its food?
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Which tissue makes up the husk of coconut?
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How many types of elements together make up the xylem tissue? Name them.
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How are simple tissues different from complex tissues in plants?
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Differentiate between parenchyma, collenchyma and sclerenchyma on the basis of their cell wall.
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What are the functions of the stomata?
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Name the tissue that transports food in plants.
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Identify the type of tissue in the bark of tree.
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Identify the type of tissue in the vascular bundle.
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Name the regions in which parenchyma tissue is present.
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What is the role of epidermis in plants?
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How does the cork act as a protective tissue?
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