The Greenhouse Effect: How greenhouse gases trap heat and warm the Earth.

Let's solve the worksheet step by step and explain each answer.

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Q.1. Fill in the blanks with suitable words.

a) ________ is the mixture of gases that surrounds the Earth.

✔ Answer: *The atmosphere*

🔹 Explanation: The atmosphere is the layer of gases that surrounds the Earth, composed mainly of nitrogen (78%), oxygen (21%), and trace amounts of other gases like carbon dioxide, water vapor, and argon.

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b) The Earth, our planet, absorbs energy from ________ in the form of solar radiation.

✔ Answer: *the Sun*

🔹 Explanation: The Earth receives energy from the Sun in the form of solar radiation (mostly visible light and some infrared and ultraviolet radiation). This energy is absorbed by the Earth’s surface and atmosphere.

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c) About 30 percent of incoming solar energy is ________ back into space.

✔ Answer: *reflected*

🔹 Explanation: Approximately 30% of the sunlight that reaches Earth is reflected back into space by clouds, ice, snow, and other reflective surfaces. This process is called albedo.

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d) A greenhouse is made up of glass panes which allow sunlight through and trap heat inside. ________ in the atmosphere, like the glass panes in a greenhouse, lets in sunlight and trap the heat energy escaping from the Earth. As a result, the temperature of Earth ________.

✔ Answer:
- First blank: *Greenhouse gases*
- Second blank: *increases*

🔹 Explanation:
- Greenhouse gases (like CO₂, methane, water vapor) act like the glass in a greenhouse — they allow sunlight to pass through but trap the heat radiated from the Earth’s surface.
- This process is known as the greenhouse effect, and it helps maintain Earth’s temperature at a level suitable for life.
- Without this effect, Earth would be much colder.

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Q.2. Write the major greenhouse gases in the spaces below.

From the diagram and scientific knowledge, the major greenhouse gases are:

1. Carbon dioxide (CO₂)
2. Methane (CH₄)
3. Nitrous oxide (N₂O)
4. Water vapor (H₂O)
5. Chlorofluorocarbons (CFCs) – though less abundant, they are very potent

But since there are only three boxes shown in the image, we should fill the top three most significant greenhouse gases:

✔ Answers:
- Box 1: Carbon dioxide (CO₂)
- Box 2: Methane (CH₄)
- Box 3: Water vapor (H₂O)

🔹 Explanation:
- Carbon dioxide (CO₂): Released from burning fossil fuels, deforestation, and industrial processes. It's the most significant contributor to human-induced global warming.
- Methane (CH₄): Emitted from agriculture (especially livestock), landfills, and fossil fuel extraction. It's more effective than CO₂ at trapping heat, but it stays in the atmosphere for a shorter time.
- Water vapor (H₂O): The most abundant greenhouse gas. Its concentration increases as the atmosphere warms, amplifying the greenhouse effect.

> Note: Nitrous oxide (N₂O) and CFCs are also important, but CO₂, CH₄, and H₂O are typically considered the primary ones in basic models.

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✔ Final Answers Summary:

#### Q.1
a) The atmosphere
b) from the Sun
c) is reflected
d) Greenhouse gases; increases

#### Q.2
- Carbon dioxide (CO₂)
- Methane (CH₄)
- Water vapor (H₂O)

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This completes the worksheet! Let me know if you'd like a printable version or further explanation.