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Previous Year Questions (Solved) : Concerns About Our Environment

global-warming

Madhyamik Class 10 Previous Year Questions of Chapter 1 – Concerns About Our Environment. Below are the fully solved questions of Physical Science, Chapter 1, presented in the simplest and easiest way. The solutions are provided in English, and you can also view them in Hindi, Bengali, and Urdu by clicking on the top-right menu icon.

  1. Write down the formula of Fire ice. How is methane gas obtained from it ?

    Answer

    Fire ice is the common name for methane hydrate.

    Chemical formula: CH4·nH2O

    Methane gas is obtained from fire ice by heating or by reducing pressure.

  2. In which layer of the atmosphere is the minimum temperature noted?

    OR

    In which layer of the atmosphere does the orbit of the International Space Station lie ?

    Answer

    Minimum temperature is noted in the mesosphere (-95ºC).

    OR

    The orbit of the International Space Station lies in the thermosphere.

  3. Chlorine atom (Cl) destroys Ozone molecule (O3) – show with the help of a chemical reaction.

    Answer

    Chlorine reacts with ozone:

    Cl + O3 → ClO + O2

    Chlorine monoxide reacts with another ozone molecule:

    ClO + O3 → Cl + 2O2

  4. The major constituent of Biogas is

    (a) CH4

    (b) CFC

    (c) CO2

    (d) CO

    Answer

    (a) CH4

    Explanation

    Biogas primarily consists of methane (CH4), with small amounts of other gases like carbon dioxide (CO2). Methane is the main combustible component.

  5. Give two reasons in favour of using paper for packaging.

    Answer

    Reasons for Using Paper for Packaging:

    1. Biodegradable: Paper is biodegradable and breaks down naturally, reducing environmental impact compared to plastic packaging.
    2. Recyclable: Paper can be easily recycled, promoting sustainability and reducing the need for new raw materials.

  6. The amount of which greenhouse gas in the atmosphere increases by the burning of fossil fuel?

    Answer

    Carbon dioxide.

  7. Mention two possible future effects of global warming on environment.

    Answer

    Two possible future effects of global warming on the environment are:

    • Increased Sea Level Rise: Melting ice caps will lead to coastal flooding and erosion.
    • Extreme Weather Events: Global warming will cause more frequent and intense hurricanes, droughts, and heatwaves.

  8. What is meant by the calorific value of a sample of coal is 30,000 kJkg-1?

    OR

    Why can wind energy be used for sustainable growth development? 

    Answer

    The calorific value of a sample of coal being 30,000 kJ/kg means that when one kilogram of this coal is completely burned, it releases 30,000 kilojoules of energy in the form of heat.

    Wind energy can be used for sustainable growth development because it is a renewable resource.

  9. Name a gas present in the atmosphere which is not a greenhouse gas.

    Answer

    Nitrogen (N2).

  10. Which of the following gases helps in the depletion of ozone in the ozone layer?

    1. CO2
    2. Ar
    3. CFCs
    4. He
    Answer

    c. CFCs

    Explanation:

    CFCs (chlorofluorocarbons) are the gases responsible for the depletion of the ozone layer. When released into the atmosphere, CFCs eventually reach the stratosphere, where they are broken down by ultraviolet (UV) light, releasing chlorine atoms. These chlorine atoms then react with ozone (O3) molecules, leading to the depletion of the ozone layer.  

  11. Which type of energy is transformed to electrical energy in a dynamo?

    Answer

    In a dynamo, mechanical energy is transformed into electrical energy.

  12. What is the SI unit of calorific value of fuels?

    Answer

    The SI unit of calorific value of fuels is joules per kilogram (J/kg).

  13. What is global warming?

    Answer

    Global warming is the gradual increase in Earth’s average surface temperature due to the buildup of greenhouse gases, such as carbon dioxide (CO2) and methane (CH4), in the atmosphere. These gases trap heat from the sun, causing a rise in temperature, which leads to climate changes like melting ice caps, rising sea levels, and more extreme weather patterns.

  14. Write the name of a gas which increases atmospheric temperature.   [1]

    OR

    Fill in the blank :   [1]

    __ radiation, coming from the sun is prevented by the ozone layer from falling on the earth’s surface.

    Answer

    A gas that increases atmospheric temperature is carbon dioxide (CO2)

    OR

    Ultraviolet (UV) radiation, coming from the sun, is prevented by the ozone layer from falling on the earth’s surface.

  15. Mention one fuel which is alternative to fossil fuel

    Answer

    One alternative fuel to fossil fuels is biofuel.

  16. Which layer of atmosphere has the greatest density?

    (a) Troposphere

    (b) Stratosphere

    (c) Mesosphere

    (d) Thermosphere

    Answer

    a. Troposphere

    Explanation:

    The troposphere is the lowest layer of Earth’s atmosphere and contains approximately 75% of the atmosphere’s mass, making it the densest layer.

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