Olympiad Test Level 1: Our Earth and Universe- 1 - Class 7 MCQ

The third layer of the Earth which comes after the Mantle of the Earth is known as the outer core.

The Earth has several layers, each with its own composition and characteristics. The layers, in order from the surface to the center, are the crust, mantle, outer core, and inner core. The mantle is located between the crust and the outer core.

Here is a breakdown of the layers of the Earth:
- Crust: The outermost layer of the Earth. It is relatively thin compared to the other layers and consists of solid rock. The crust is divided into two types: continental crust and oceanic crust.
- Mantle: The layer beneath the crust. It is the thickest layer of the Earth and is composed of solid rock that is capable of flowing under high pressure and temperature. The mantle is further divided into the upper mantle and the lower mantle.
- Outer Core: The layer that comes after the mantle. It is a liquid layer composed mainly of molten iron and nickel. The outer core is responsible for generating the Earth's magnetic field through the movement of electrically conductive materials.
- Inner Core: The innermost layer of the Earth. It is a solid sphere composed mainly of iron and nickel. Despite the extremely high temperature, the inner core remains solid due to the immense pressure it experiences.
In summary, the third layer of the Earth which comes after the Mantle of the Earth is known as the outer core.

Explanation:
The plates of the Earth move apart from each other due to convection currents. Here is a detailed explanation of why this happens:
1. Convection currents: Convection currents occur in the Earth's mantle, which is the layer between the Earth's crust and core. These currents are caused by the transfer of heat from the hotter interior of the Earth to the cooler surface.
2. Mantle convection: The convection currents in the mantle are driven by the heat generated from the radioactive decay of elements and residual heat from the formation of the Earth. This heat causes the mantle material to become less dense and rise towards the surface.
3. Upwelling and spreading: As the hot mantle material rises towards the surface, it creates upwelling zones where the plates are moving apart. These upwelling zones are known as divergent boundaries.
4. Divergent boundaries: At divergent boundaries, the plates move apart from each other. As the plates separate, magma from the mantle rises to fill the gap, creating new crust. This process is known as seafloor spreading.
5. Creation of new crust: The upwelling of mantle material at divergent boundaries leads to the creation of new crust. This new crust pushes the existing plates apart, causing them to move away from each other.
In conclusion, the plates of the Earth move apart from each other due to convection currents in the mantle. These currents create upwelling zones at divergent boundaries, where new crust is formed and pushes the plates apart.

To determine the total surface area of the Earth, we need to consider both land and water areas. Here's how we can calculate it:
1. Calculate the land area:
- The total land area of the Earth is approximately 148.94 million square kilometers.
- This includes all continents, islands, and other landmasses.
2. Calculate the water area:
- The total water area of the Earth is approximately 361.13 million square kilometers.
- This includes all oceans, seas, lakes, and rivers.
3. Add the land and water areas together:
- 148.94 million sq km (land area) + 361.13 million sq km (water area) = 510.07 million square kilometers.
Therefore, the correct answer is option A: 510 million sq km.

The planet known as Earth's twin is Venus.
Explanation:
- Venus is often referred to as Earth's twin because it is similar in size and composition to our planet.
- Both Venus and Earth are rocky planets and are located within the Sun's habitable zone.
- Venus has a similar mass and density to Earth, and it also has a similar gravity.
- Venus and Earth are also similar in terms of their chemical composition, with both planets having a primarily carbon dioxide atmosphere.
- Venus is often considered Earth's twin because of these similarities, although there are also significant differences between the two planets.
- For example, Venus has a much higher surface temperature, a thicker atmosphere, and a runaway greenhouse effect that has led to a hostile environment on the planet.
- Despite these differences, Venus is still considered Earth's twin due to its similar size and composition.
In conclusion, the planet known as Earth's twin is Venus.

Explanation:
The word 'ecology' was coined in 1866 by Ernst Haeckel, a German biologist and philosopher. Here is a detailed explanation:
1. Ernst Haeckel:
- Ernst Haeckel was a prominent German biologist, zoologist, and philosopher.
- He is known for his contributions to the field of evolutionary biology and for coining the term 'ecology'.
- Haeckel first used the term 'oekologie' (later translated to 'ecology') in his work titled "Generelle Morphologie der Organismen" (1866).
2. Charles Darwin:
- Charles Darwin was an English naturalist and geologist.
- He is best known for his theory of evolution and natural selection.
- Although Darwin made significant contributions to the field of biology, he did not coin the term 'ecology'.
3. Robert Whittaker:
- Robert Whittaker was an American ecologist and plant taxonomist.
- He is known for his work on classifying ecosystems and proposing the five-kingdom classification system.
- However, Whittaker did not coin the term 'ecology'.
4. Arthur Tansley:
- Arthur Tansley was an English botanist and ecologist.
- He is credited with coining the term 'ecosystem' in 1935.
- However, Tansley did not coin the term 'ecology'.
Therefore, the correct answer is D: Ernst Haeckel. He coined the term 'ecology' in 1866 in his work on morphology and is considered one of the pioneers of the field.

Green Climate Fund
The Green Climate Fund (GCF) was proposed in the following environment conference:
Option B: 2010 United Nations Climate Change Conference
Here is a detailed explanation:
1. Background: The Green Climate Fund (GCF) is a financial mechanism established to support developing countries in their efforts to combat climate change and adapt to its impacts. It aims to promote a paradigm shift towards low-emission and climate-resilient development.
2. Proposal: The proposal for the Green Climate Fund was put forward during the 2010 United Nations Climate Change Conference, also known as COP16 (Conference of the Parties). The conference was held in Cancun, Mexico, from November 29 to December 10, 2010.
3. Objective: The Green Climate Fund was created with the objective of mobilizing funds from developed countries and channeling them to developing countries for climate change mitigation and adaptation projects. It aims to help developing countries transition to a low-carbon and climate-resilient economy.
4. Implementation: The Green Climate Fund became operational in 2015 and is governed by a board of representatives from developed and developing countries. It provides financial support through a variety of mechanisms, including grants, loans, and equity investments.
5. Key Features: The Green Climate Fund focuses on the needs of the most vulnerable countries and aims to ensure the balanced allocation of funds between mitigation and adaptation projects. It also emphasizes the importance of gender equality and the involvement of local communities in project implementation.
In conclusion, the Green Climate Fund was proposed during the 2010 United Nations Climate Change Conference (COP16) held in Cancun, Mexico. It was established to provide financial support to developing countries for climate change mitigation and adaptation projects.

The different group of stars is known as:

• Constellation: A group of stars that form a recognizable pattern or shape in the sky. Constellations are often named after mythological figures, animals, or objects.


• Celestial bodies: This term refers to all objects in space, including stars, planets, moons, asteroids, comets, and galaxies. However, stars are specifically referred to as celestial bodies.


• Asteroids: These are rocky objects that orbit the Sun, primarily found in the asteroid belt between Mars and Jupiter. They are not groups of stars, but rather small celestial bodies.


• Comets: Comets are icy objects that also orbit the Sun. When a comet gets close to the Sun, the heat causes the ice to vaporize, creating a glowing coma and tail. Again, comets are not groups of stars, but rather individual celestial bodies.

The correct answer is:

• Constellation (Option A)

In summary, constellations are the different groups of stars that form recognizable patterns in the sky, while celestial bodies refer to all objects in space, including stars. Asteroids and comets are also celestial bodies, but they are not groups of stars.

Answer:
Amirata Devi Bishnoi sacrificed her life to protect Khejri trees.
Explanation:
Amirata Devi Bishnoi, also known as the "Tree Martyr," dedicated her life to conserving the environment and protecting the Khejri trees. Here is a detailed explanation of her sacrifice and the significance of Khejri trees:
1. Amirata Devi Bishnoi:
- Amirata Devi Bishnoi was an environmental activist from Rajasthan, India.
- She belonged to the Bishnoi community, which has a long-standing tradition of protecting trees and wildlife.
- Amirata Devi Bishnoi was deeply committed to the conservation of nature and worked tirelessly to raise awareness about the importance of trees.
2. Khejri Trees:
- Khejri trees, scientifically known as Prosopis cineraria, are native to the arid regions of Rajasthan.
- They play a vital role in maintaining the ecological balance of the desert ecosystem.
- Khejri trees are highly valued for their multiple uses. They provide shade, fodder, and wood for the local communities.
- These trees have adapted to survive in extreme weather conditions and are known for their ability to withstand droughts.
3. Sacrifice:
- Amirata Devi Bishnoi made the ultimate sacrifice by laying down her life to protect the Khejri trees.
- In 1992, she tried to prevent the cutting of Khejri trees by loggers who were illegally harvesting them for commercial purposes.
- Despite her pleas and protests, the loggers proceeded with their activities, and Amirata Devi Bishnoi bravely stood in front of the tree to protect it.
- Sadly, she was brutally killed in the process, but her sacrifice brought attention to the importance of conserving trees and preserving the environment.
Conclusion:
Amirata Devi Bishnoi's sacrifice serves as a reminder of the significance of environmental conservation. Her act of bravery to protect the Khejri trees highlights the need to respect and preserve nature for sustainable development. The Khejri trees continue to be a symbol of the Bishnoi community's commitment to environmental protection.

The moon takes a certain amount of time to complete one spin, which is also known as its rotation period. To determine the correct answer, we need to consider the options provided and evaluate each one.
Given options:
A: 26
B: 25
C: 28
D: 27
Evaluating the options:
To find the correct answer, we need to know the actual rotation period of the moon. The rotation period of the moon is approximately 27.3 days. Therefore, the correct answer is D: 27.
Explanation:
Here is why the other options are incorrect:
A: 26 - This option is incorrect because the actual rotation period of the moon is not 26 days.
B: 25 - This option is incorrect because the actual rotation period of the moon is not 25 days.
C: 28 - This option is incorrect because the actual rotation period of the moon is not 28 days.
In conclusion, the moon takes approximately 27.3 days to complete one spin or rotation.