6th Science - 2nd Mid Term Exam 2024 - Original Question Paper | Krishnagiri District | English Medium

STD: 6 | SECOND MID TERM EXAM - NOVEMBER 2024 | SCIENCE - SOLUTIONS

I. CHOOSE THE CORRECT ANSWER (5 X 1 = 5)

1. One litre of water at 30°C is mixed with one litre of water at 50°C. The temperature of the mixture will be _______.
   • (a) 80°C
   • (b) More than 50°C but less than 80°C
   • (c) 20°C
   • (d) around 40°C

   (d) around 40°C

   Explanation: When equal quantities of hot and cold water are mixed, the final temperature will be the average of the two initial temperatures. (30°C + 50°C) / 2 = 40°C.

2. The device which converts chemical energy into electrical energy is _______.
   • (a) Fan
   • (b) solar cell
   • (c) cell
   • (d) television

   (c) cell

3. Out of the following an example of a desirable change is _______.
   • (a) rusting
   • (b) change of seasons
   • (c) earthquake
   • (d) flooding

   (b) change of seasons

4. The gas given out during photosynthesis is _______.
   • (a) carbon-di-oxide
   • (b) Nitrogen
   • (c) ozone
   • (d) Oxygen

   (d) Oxygen

5. Which one of the following is not an unicellular organism?
   • (a) Yeast
   • (b) Amoeba
   • (c) spirogyra
   • (d) Bacteria

   (c) spirogyra

   Explanation: Spirogyra is a multicellular green alga.

II. Fill in the blanks (5 X 1 = 5)

6. The SI unit of temperature is Kelvin.
7. The combination of two or more cells is called a battery.
8. Boiling of egg results in irreversible / chemical change.
9. Carbon dioxide Gas turns lime water milky.
10. The egg of an Ostrich is the largest single cell.

III. Match the following (5 X 1 = 5)

Here are the correct matches for the symbols and their descriptions.

Solution

IV. Write any 5 questions only (5 X 2 = 10)

12. What is temperature?

    Temperature is the measure of the degree of hotness or coldness of a body. It indicates the average kinetic energy of the particles in a substance.

13. Distinguish between heat and temperature.

    Heat	Temperature
    It is a form of energy that flows from a hotter body to a colder body.	It is the degree of hotness or coldness of a body.
    Its SI unit is Joule (J).	Its SI unit is Kelvin (K).

14. Circle the odd one out. Give reason for your choice. Switch, Bulb, Battery, Generator.

    Odd one out: Generator

    Reason: Switch, Bulb, and Battery are components used in a simple electrical circuit that consume or control stored energy. A Generator, on the other hand, produces electrical energy, typically by converting mechanical energy into electrical energy.

15. Arrange in sequence

    Jumbled words: A CELL A DEVICE ELECTRICAL ENERGY IS CALLED IN TO CHEMICAL ENERGY THAT CONVERTS

    Correct sequence: A cell is a device that converts chemical energy into electrical energy.

16. Define a slow change.

    A change that takes place over a long period of time, such as hours, days, months, or years, is called a slow change. Examples include the rusting of iron and the growth of a plant.

17. What happens when paper is burnt?

    When paper is burnt, it undergoes an irreversible chemical change. It reacts with oxygen in the air and is converted into new substances like ash, carbon dioxide, and water vapour. Heat and light are also produced during this process.

18. Arrange in a correct sequence

    (a) Elephant, cow, Bacteria, Mango, Rose plant.

    Correct Sequence (from simple to complex): Bacteria → Rose plant → Mango → Cow → Elephant.

    (b) Hen's Egg, Ostrich's egg, Insect's egg.

    Correct Sequence (by increasing size): Insect's egg → Hen's Egg → Ostrich's egg.

19. Analogy:

    (a) Prokaryote: Bacteria; Eukaryote: Amoeba / Plant Cell / Animal Cell

    (b) Food producer: Chloroplasts; Power house: Mitochondria

V. Write any 1 question only (1 X 5 = 5)

20. Explain thermal expansion with suitable examples.

    Thermal expansion is the tendency of matter to change its shape, area, volume, and density in response to a change in temperature. Most substances expand when heated and contract when cooled.

    Examples:

    • Railway Tracks: Small gaps, called expansion gaps, are deliberately left between sections of railway tracks. In summer, the tracks get hot and expand. These gaps provide space for the expansion, preventing the tracks from bending.
    • Thermometer: In a mercury or alcohol thermometer, the liquid inside the glass tube expands when it gets hotter, causing the level to rise. It contracts when it cools, causing the level to fall.

21. Give one example for each case that happens around you.

    (a) slow and fast change

    • Slow change: Growth of a tree.
    • Fast change: Bursting of a firecracker.

    (b) Reversible and Irreversible change.

    • Reversible change: Melting of ice into water (can be frozen back to ice).
    • Irreversible change: Cooking rice (cooked rice cannot be turned back into raw rice).

    (c) Decaying of food .......... change (Desirable / Undesirable)

    • Decaying of food is an Undesirable change.

22. Identify any Five parts of the Plant cell.

    Using the provided diagram and list (Golgi apparatus, Chloroplast, Nucleus, Nucleolus, Endoplasmic Reticulum, cell wall, Mitochondria), here are five identifiable parts of a typical plant cell:

    
    1. Cell Wall: The rigid outer layer that provides structural support and protection to the cell.
    2. Nucleus: The large, often spherical organelle that contains the cell's genetic material and controls its activities.
    3. Chloroplast: Small, green, disc-shaped organelles where photosynthesis takes place.
    4. Mitochondria: The "powerhouse" of the cell, responsible for generating energy through cellular respiration.
    5. Endoplasmic Reticulum: A network of membranes involved in protein and lipid synthesis.