EXPERIMENT–5 (PHYSICS)
To determine the melting point of ice
Object:
To find the temperature at which ice melts and to study the change of state from solid to liquid.
Apparatus Required:
Beaker, clean crushed ice, thermometer, glass rod.
Theory:
The melting point is defined as the temperature at which a solid changes into a liquid under normal atmospheric pressure. When ice is heated, its temperature increases until it reaches 0°C. At this point, the ice begins to melt and the temperature remains unchanged until all the ice is converted into water. This constant temperature is known as the melting point of ice.
Observation:
During heating, the thermometer reading increases and then stays fixed at 0°C while the ice changes into water.
Result:
The melting point of ice is observed to be 0°C.
Conclusion:
Ice melts and changes into water at a constant temperature of 0°C.
Precautions:
• Use pure and finely crushed ice.
• Ensure the thermometer bulb does not touch the beaker.
•Stir gently for uniform temperature.
EXPERIMENT–13 (CHEMISTRY)
To Differentiate between a Chemical and Physical Change in a Given Process
Object:
To distinguish between physical and chemical changes using iron and sulphur.
Apparatus Required:
Iron filings, sulphur powder, test tube, burner, magnet.
Theory:
A physical change does not form a new substance and is generally reversible, while a chemical change forms a new substance and is irreversible. When iron and sulphur are mixed, only a physical change takes place. On heating, they chemically react to form iron sulphide, which is a new substance.
Observation:
Before heating, iron particles can be separated using a magnet. After heating, a black substance (iron sulphide) is formed which cannot be separated by a magnet.
Result:
Heating the mixture of iron and sulphur results in a chemical change.
Conclusion:
Chemical changes produce new substances with different properties.
Precautions:
• Heat the mixture slowly and carefully.
• Handle the hot test tube properly.
• Use a small amount of chemicals.
EXPERIMENT–17 (CHEMISTRY)
To test the acidic or basic nature of a solution with the help of pH paper
Object:
To find whether the given solution is acidic or basic using pH paper.
Apparatus Required:
pH paper strips, test solution, dropper.
Theory:
pH paper contains special indicators that show different colours in acidic, basic, and neutral solutions. The colour obtained is matched with the pH scale to identify the nature of the solution.
Observation:
The pH paper changes colour when placed in the test solution.
Result:
The solution is identified as acidic or basic based on the colour change.
Conclusion:
pH paper provides a simple and effective way to test the nature of solutions.
Precautions:
• Do not touch the pH paper with bare hands.
• Use a clean dropper.
• Compare the colour immediately.
EXPERIMENT–25 (BIOLOGY)
To show that oxygen is released during photosynthesis
Object:
To demonstrate that oxygen gas is released during photosynthesis.
Apparatus Required:
Hydrilla plant, beaker, funnel, test tube, water.
Theory:
Photosynthesis is the process in which green plants make food using sunlight and chlorophyll. During this process, oxygen is released as a by-product.
Observation:
Gas bubbles are seen coming out from the plant and are collected in the test tube.
Result:
Oxygen gas is produced during photosynthesis.
Conclusion:
In the presence of sunlight, photosynthesis results in the release of oxygen.
Precautions:
• Use a healthy green plant.
• Provide sufficient sunlight.
• Remove trapped air bubbles at the start.
EXPERIMENT–26 (BIOLOGY)
To show that carbon dioxide is released during respiration
Object:
To demonstrate that carbon dioxide gas is released during respiration.
Apparatus Required:
Germinating seeds, conical flask, lime water, cork, delivery tube.
Theory:
Respiration is the process by which food is broken down to release energy. During respiration, carbon dioxide is produced as a waste gas, which turns lime water milky.
Observation:
Lime water turns milky when the gas released from germinating seeds passes through it.
Result:
Carbon dioxide gas is released during respiration.
Conclusion:
Living organisms release carbon dioxide during respiration.
Precautions:
• Use actively germinating seeds.
• Ensure the setup is airtight.
• Use fresh lime water.
