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

Standard 6 SCIENCE - Solved Paper

Virudhunagar District

Common Second Mid Term Test - 2024

Time: 1.30 Hrs. Marks: 30

I. Choose the correct answer: 4x1=4

1) The unit of heat is ______.

• a) newton
• b) joule
• c) volt
• d) celsius

Answer: b) joule

2) The device which converts chemical energy into electrical energy is ______.

• a) fan
• b) solar cell
• c) cell
• d) television

Answer: c) cell

3) Air pollution leading to Acid rain is a ______.

• a) reversible change
• b) fast change
• c) natural change
• d) human made change

Answer: d) human made change

4) The unit of measurement used for expressing dimension of the cell is ______.

• a) centimeter
• b) millimeter
• c) micrometer
• d) meter

Answer: c) micrometer

II. Fill in the blanks with correct answer: 2x1=2

5) Solids ______ on heating and ______ on cooling.

Answer: Solids expand on heating and contract on cooling.

6) Changes that are harmful to us are ______ (desirable / undesirable).

Answer: Changes that are harmful to us are undesirable.

III. True or False. If false, give the correct answer: 2x1=2

7) The switch is used to close or open an electric circuit.

Answer: True.

8) A cell is the smallest unit of life.

Answer: True.

IV. Analogy: 2x1=2

9) Ice cube : 0°C :: Boiling water : ______

Answer: 100°C

10) Burning of match stick : ______ change :: Rotation of the Earth : Slow change

Answer: Fast

V. Answer any five questions: Question No. 18 is compulsory 5x2=10

11) What is Thermal Expansion?

Answer: Thermal expansion is the tendency of matter to change its shape, area, volume, and density in response to a change in temperature. When a substance is heated, its particles move faster and farther apart, causing the substance to expand.

12) Can the cell used in the clock gives us an electric shock? Justify your answer.

Answer: No, the cell used in a clock cannot give us an electric shock. This is because it has a very low voltage (typically 1.5V) and produces a very low current. The human body has high resistance, and this low voltage is insufficient to push a noticeable current through it.

13) Define a slow change.

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

14) What is a solution?

Answer: A solution is a homogeneous mixture of two or more substances. In a solution, the substance that is dissolved is called the solute, and the substance in which the solute is dissolved is called the solvent. For example, in salt water, salt is the solute and water is the solvent.

15) What happens when paper is burnt? Explain.

Answer: 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, water vapour, smoke. Heat and light are also produced during this process. The original paper cannot be obtained back from these new substances.

16) Why are cells called building blocks of life?

Answer: Cells are called the building blocks of life because all living organisms, from the smallest bacteria to the largest animals, are made up of one or more cells. Just as bricks are assembled to make a building, cells are organized to form tissues, organs, and entire organisms. They are the basic structural and functional units of all known organisms.

17) Identify any four parts of the plant cell.

Answer: Four main parts of a plant cell are:

1. Cell Wall
2. Cell Membrane
3. Cytoplasm
4. Nucleus

(Other valid answers include Chloroplast, Vacuole).

18) Draw the circuit diagram for series connection.

Answer: A circuit diagram for a series connection shows the components connected end-to-end, forming a single path for the current to flow. The diagram should include a cell (or battery), a switch, and at least two bulbs connected in a line.

[Image of a series circuit diagram]

Components: A battery, a switch, and two bulbs connected in a single loop.

VI. Answer any two questions only: 2x5=10

19) Explain the thermal expansion with suitable examples.

Answer: Thermal expansion is the increase in the size (length, area, or volume) of a body due to an increase in its temperature.

Explanation: When we heat a substance, the kinetic energy of its particles (atoms or molecules) increases. This causes them to vibrate more vigorously and move farther apart from each other, resulting in the expansion of the substance.

Suitable Examples:

• Railway Tracks: Small gaps, called expansion gaps, are left between sections of railway tracks. In summer, the tracks heat up and expand. These gaps provide space for the expansion, preventing the tracks from buckling.
• Thermometer: In a mercury or alcohol thermometer, the liquid inside the glass tube expands when it gets hotter. This expansion causes the liquid level to rise, indicating the temperature.
• Fitting a metal rim on a wooden wheel: A metal rim is made slightly smaller than the wooden wheel. It is then heated, causing it to expand. The hot rim is placed over the wheel, and as it cools, it contracts and fits tightly onto the wheel.

20) Write short notes on Conductors and Insulators.

Conductors:

Conductors are materials that allow electric current to pass through them easily. They have free electrons that can move through the material, carrying the electric charge. Most metals are good conductors.

• Properties: Low electrical resistance.
• Examples: Copper, Aluminium, Silver, Gold, Iron, Human Body, Tap Water.
• Uses: Used in making electrical wires, circuits, and heating elements.

Insulators:

Insulators are materials that do not allow electric current to pass through them. Their electrons are tightly bound to the atoms and are not free to move. They have very high electrical resistance.

• Properties: High electrical resistance.
• Examples: Plastic, Rubber, Wood, Glass, Ceramic, Pure Water, Air.
• Uses: Used as protective coatings for electrical wires (e.g., plastic insulation), handles for tools (e.g., screwdriver handle), and in safety equipment.

21) Give one example in 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 to form water.
  • Irreversible Change: Cooking rice.
• c) Physical and Chemical change:
  • Physical Change: Tearing a piece of paper.
  • Chemical Change: Rusting of an iron nail.
• d) Natural and Man-made change:
  • Natural Change: A flower blooming.
  • Man-made Change: Constructing a building.
• e) Desirable and Undesirable change:
  • Desirable Change: Ripening of mangoes.
  • Undesirable Change: Spoiling of milk.

22) Draw a neat labelled diagram of a Prokaryotic cell.

Answer: A prokaryotic cell is a simple cell that lacks a true nucleus and other membrane-bound organelles.

[Image of a labelled Prokaryotic Cell]

Key Labels:

• Cell Wall: Outer protective layer.
• Plasma Membrane: Inner membrane controlling substance movement.
• Cytoplasm: Jelly-like substance filling the cell.
• Nucleoid: Region containing the single, circular DNA.
• Ribosomes: Sites of protein synthesis.
• Flagellum: (Optional) Whip-like tail for movement.